Virgin import of FSF groff v1.19.2

1 files changed, 7487 insertions, 177 deletions

diff --git a/contrib/groff/doc/groff-1 b/contrib/groff/doc/groff-1
index 948cc6a..04207e4 100644
--- a/contrib/groff/doc/groff-1
+++ b/contrib/groff/doc/groff-1
@@ -1,9 +1,9 @@
-This is groff, produced by makeinfo version 4.3d from ./groff.texinfo.
+This is groff, produced by makeinfo version 4.8 from ./groff.texinfo.
 
-This manual documents GNU `troff' version 1.19.
+   This manual documents GNU `troff' version 1.19.2.
 
-   Copyright (C) 1994-2000, 2001, 2002, 2003 Free Software Foundation,
-Inc.
+   Copyright (C) 1994-2000, 2001, 2002, 2003, 2004, 2005 Free Software
+Foundation, Inc.
 
      Permission is granted to copy, distribute and/or modify this
      document under the terms of the GNU Free Documentation License,
@@ -16,7 +16,7 @@ Inc.
      (a) The FSF's Back-Cover Text is: `You have freedom to copy and
      modify this GNU Manual, like GNU software.  Copies published by
      the Free Software Foundation raise funds for GNU development."
-   
+
 INFO-DIR-SECTION Typesetting
 START-INFO-DIR-ENTRY
 * Groff: (groff).               The GNU troff document formatting system.
@@ -28,10 +28,10 @@ File: groff,  Node: Top,  Next: Introduction,  Prev: (dir),  Up: (dir)
 GNU troff
 *********
 
-This manual documents GNU `troff' version 1.19.
+This manual documents GNU `troff' version 1.19.2.
 
-   Copyright (C) 1994-2000, 2001, 2002, 2003 Free Software Foundation,
-Inc.
+   Copyright (C) 1994-2000, 2001, 2002, 2003, 2004, 2005 Free Software
+Foundation, Inc.
 
      Permission is granted to copy, distribute and/or modify this
      document under the terms of the GNU Free Documentation License,
@@ -44,7 +44,7 @@ Inc.
      (a) The FSF's Back-Cover Text is: `You have freedom to copy and
      modify this GNU Manual, like GNU software.  Copies published by
      the Free Software Foundation raise funds for GNU development."
-   
+
 * Menu:
 
 * Introduction::
@@ -71,10 +71,10 @@ Inc.
 
 File: groff,  Node: Introduction,  Next: Invoking groff,  Prev: Top,  Up: Top
 
-Introduction
-************
+1 Introduction
+**************
 
-   GNU `troff' (or `groff') is a system for typesetting documents.
+GNU `troff' (or `groff') is a system for typesetting documents.
 `troff' is very flexible and has been in existence (and use) for about
 3 decades.  It is quite widespread and firmly entrenched in the UNIX
 community.
@@ -92,16 +92,16 @@ community.
 
 File: groff,  Node: What Is groff?,  Next: History,  Prev: Introduction,  Up: Introduction
 
-What Is `groff'?
-================
+1.1 What Is `groff'?
+====================
 
-   `groff' belongs to an older generation of document preparation
-systems, which operate more like compilers than the more recent
-interactive WYSIWYG(1) (*note What Is groff?-Footnote-1::) systems.
-`groff' and its contemporary counterpart, TeX, both work using a
-"batch" paradigm: The input (or "source") files are normal text files
-with embedded formatting commands.  These files can then be processed
-by `groff' to produce a typeset document on a variety of devices.
+`groff' belongs to an older generation of document preparation systems,
+which operate more like compilers than the more recent interactive
+WYSIWYG(1) (*note What Is groff?-Footnote-1::) systems.  `groff' and
+its contemporary counterpart, TeX, both work using a "batch" paradigm:
+The input (or "source") files are normal text files with embedded
+formatting commands.  These files can then be processed by `groff' to
+produce a typeset document on a variety of devices.
 
    Likewise, `groff' should not be confused with a "word processor",
 since that term connotes an integrated system that includes an editor
@@ -135,10 +135,10 @@ File: groff,  Node: What Is groff?-Footnotes,  Up: What Is groff?
 
 File: groff,  Node: History,  Next: groff Capabilities,  Prev: What Is groff?,  Up: Introduction
 
-History
-=======
+1.2 History
+===========
 
-   `troff' can trace its origins back to a formatting program called
+`troff' can trace its origins back to a formatting program called
 `runoff', written by J. E. Saltzer, which ran on MIT's CTSS operating
 system in the mid-sixties.  This name came from the common phrase of
 the time "I'll run off a document."  Bob Morris ported it to the 635
@@ -176,7 +176,7 @@ changes).
 transform certain parts of a document into `troff', which made a very
 natural use of pipes in UNIX.
 
-   The `eqn' preprocessor allowed mathematical formulae to be specified
+   The `eqn' preprocessor allowed mathematical formulæ to be specified
 in a much simpler and more intuitive manner.  `tbl' is a preprocessor
 for formatting tables.  The `refer' preprocessor (and the similar
 program, `bib') processes citations in a document according to a
@@ -238,11 +238,11 @@ produce HTML output have been added.
 
 File: groff,  Node: groff Capabilities,  Next: Macro Package Intro,  Prev: History,  Up: Introduction
 
-`groff' Capabilities
-====================
+1.3 `groff' Capabilities
+========================
 
-   So what exactly is `groff' capable of doing?  `groff' provides a
-wide range of low-level text formatting operations.  Using these, it is
+So what exactly is `groff' capable of doing?  `groff' provides a wide
+range of low-level text formatting operations.  Using these, it is
 possible to perform a wide range of formatting tasks, such as
 footnotes, table of contents, multiple columns, etc.  Here's a list of
 the most important operations supported by `groff':
@@ -288,10 +288,10 @@ the most important operations supported by `groff':
 
 File: groff,  Node: Macro Package Intro,  Next: Preprocessor Intro,  Prev: groff Capabilities,  Up: Introduction
 
-Macro Packages
-==============
+1.4 Macro Packages
+==================
 
-   Since `groff' provides such low-level facilities, it can be quite
+Since `groff' provides such low-level facilities, it can be quite
 difficult to use by itself.  However, `groff' provides a "macro"
 facility to specify how certain routine operations (e.g. starting
 paragraphs, printing headers and footers, etc.)  should be done.  These
@@ -302,15 +302,15 @@ described in this manual) are `man', `mdoc', `me', `ms', and `mm'.
 
 File: groff,  Node: Preprocessor Intro,  Next: Output device intro,  Prev: Macro Package Intro,  Up: Introduction
 
-Preprocessors
-=============
+1.5 Preprocessors
+=================
 
-   Although `groff' provides most functions needed to format a
-document, some operations would be unwieldy (e.g. to draw pictures).
-Therefore, programs called "preprocessors" were written which
-understand their own language and produce the necessary `groff'
-operations.  These preprocessors are able to differentiate their own
-input from the rest of the document via markers.
+Although `groff' provides most functions needed to format a document,
+some operations would be unwieldy (e.g. to draw pictures).  Therefore,
+programs called "preprocessors" were written which understand their own
+language and produce the necessary `groff' operations.  These
+preprocessors are able to differentiate their own input from the rest
+of the document via markers.
 
    To use a preprocessor, UNIX pipes are used to feed the output from
 the preprocessor into `groff'.  Any number of preprocessors may be used
@@ -335,24 +335,24 @@ drawing mathematical pictures (`ideal') and chemical structures
 
 File: groff,  Node: Output device intro,  Next: Credits,  Prev: Preprocessor Intro,  Up: Introduction
 
-Output Devices
-==============
+1.6 Output Devices
+==================
 
-   `groff' actually produces device independent code which may be fed
-into a postprocessor to produce output for a particular device.
-Currently, `groff' has postprocessors for POSTSCRIPT devices, character
-terminals, X Windows (for previewing), TeX DVI format, HP LaserJet 4
-and Canon LBP printers (which use CAPSL), and HTML.
+`groff' actually produces device independent code which may be fed into
+a postprocessor to produce output for a particular device.  Currently,
+`groff' has postprocessors for POSTSCRIPT devices, character terminals,
+X Windows (for previewing), TeX DVI format, HP LaserJet 4 and Canon LBP
+printers (which use CAPSL), and HTML.
 
 
 File: groff,  Node: Credits,  Prev: Output device intro,  Up: Introduction
 
-Credits
-=======
+1.7 Credits
+===========
 
-   Large portions of this manual were taken from existing documents,
-most notably, the manual pages for the `groff' package by James Clark,
-and Eric Allman's papers on the `me' macro package.
+Large portions of this manual were taken from existing documents, most
+notably, the manual pages for the `groff' package by James Clark, and
+Eric Allman's papers on the `me' macro package.
 
    The section on the `man' macro package is partly based on Susan G.
 Kleinmann's `groff_man' manual page written for the Debian GNU/Linux
@@ -363,10 +363,10 @@ system.
 
 File: groff,  Node: Invoking groff,  Next: Tutorial for Macro Users,  Prev: Introduction,  Up: Top
 
-Invoking `groff'
-****************
+2 Invoking `groff'
+******************
 
-   This section focuses on how to invoke the `groff' front end.  This
+This section focuses on how to invoke the `groff' front end.  This
 front end takes care of the details of constructing the pipeline among
 the preprocessors, `gtroff' and the postprocessor.
 
@@ -398,10 +398,10 @@ called AT&T `troff' which is the common origin of all `troff' derivates
 
 File: groff,  Node: Groff Options,  Next: Environment,  Prev: Invoking groff,  Up: Invoking groff
 
-Options
-=======
+2.1 Options
+===========
 
-   `groff' normally runs the `gtroff' program and a postprocessor
+`groff' normally runs the `gtroff' program and a postprocessor
 appropriate for the selected device.  The default device is `ps' (but
 it can be changed when `groff' is configured and built).  It can
 optionally preprocess with any of `gpic', `geqn', `gtbl', `ggrn',
@@ -483,7 +483,9 @@ to format a file.
      Make programs run by `groff' print out their version number.
 
 `-V'
-     Print the pipeline on `stdout' instead of executing it.
+     Print the pipeline on `stdout' instead of executing it.  If
+     specified more than once, print the pipeline on `stderr' and
+     execute it.
 
 `-z'
      Suppress output from `gtroff'.  Only error messages are printed.
@@ -683,17 +685,31 @@ to format a file.
      directories (*note Macro Directories::).
 
 `-IDIR'
-     This option is as described in *Note gsoelim::.  It implies the
-     `-s' option.
+     This option may be used to specify a directory to search for files.
+     It is passed to the following programs:
+
+        * `gsoelim' (see *Note gsoelim:: for more details); it also
+          implies `groff''s `-s' option.
+
+        * `gtroff'; it is used to search files named in the `psbb' and
+          `so' requests.
+
+        * `grops'; it is used to search files named in the
+          `\X'ps: import' and `\X'ps: file' escapes.
+
+     The current directory is always searched first. This option may be
+     specified more than once; the directories will be searched in the
+     order specified. No directory search is performed for files
+     specified using an absolute path.
 
 
 File: groff,  Node: Environment,  Next: Macro Directories,  Prev: Groff Options,  Up: Invoking groff
 
-Environment
-===========
+2.2 Environment
+===============
 
-   There are also several environment variables (of the operating
-system, not within `gtroff') which can modify the behavior of `groff'.
+There are also several environment variables (of the operating system,
+not within `gtroff') which can modify the behavior of `groff'.
 
 `GROFF_COMMAND_PREFIX'
      If this is set to X, then `groff' runs `Xtroff' instead of
@@ -737,13 +753,13 @@ above.
 
 File: groff,  Node: Macro Directories,  Next: Font Directories,  Prev: Environment,  Up: Invoking groff
 
-Macro Directories
-=================
+2.3 Macro Directories
+=====================
 
-   All macro file names must be named `NAME.tmac' or `tmac.NAME' to
-make the `-mNAME' command line option work.  The `mso' request doesn't
-have this restriction; any file name can be used, and `gtroff' won't
-try to append or prepend the `tmac' string.
+All macro file names must be named `NAME.tmac' or `tmac.NAME' to make
+the `-mNAME' command line option work.  The `mso' request doesn't have
+this restriction; any file name can be used, and `gtroff' won't try to
+append or prepend the `tmac' string.
 
    Macro files are kept in the "tmac directories", all of which
 constitute the "tmac path".  The elements of the search path for macro
@@ -776,17 +792,16 @@ files are (in that order):
 
 File: groff,  Node: Font Directories,  Next: Paper Size,  Prev: Macro Directories,  Up: Invoking groff
 
-Font Directories
-================
+2.4 Font Directories
+====================
 
-   Basically, there is no restriction how font files for `groff' are
-named and how long font names are; however, to make the font family
-mechanism work (*note Font Families::), fonts within a family should
-start with the family name, followed by the shape.  For example, the
-Times family uses `T' for the family name and `R', `B', `I', and `BI'
-to indicate the shapes `roman', `bold', `italic', and `bold italic',
-respectively.  Thus the final font names are `TR', `TB', `TI', and
-`TBI'.
+Basically, there is no restriction how font files for `groff' are named
+and how long font names are; however, to make the font family mechanism
+work (*note Font Families::), fonts within a family should start with
+the family name, followed by the shape.  For example, the Times family
+uses `T' for the family name and `R', `B', `I', and `BI' to indicate
+the shapes `roman', `bold', `italic', and `bold italic', respectively.
+Thus the final font names are `TR', `TB', `TI', and `TBI'.
 
    All font files are kept in the "font directories" which constitute
 the "font path".  The file search functions will always append the
@@ -817,12 +832,12 @@ files for `grodvi' must be in `/foo/bar/devdvi'.
 
 File: groff,  Node: Paper Size,  Next: Invocation Examples,  Prev: Font Directories,  Up: Invoking groff
 
-Paper Size
-==========
+2.5 Paper Size
+==============
 
-   In groff, the page size for `gtroff' and for output devices are
-handled separately.  *Note Page Layout::, for vertical manipulation of
-the page size.  *Note Line Layout::, for horizontal changes.
+In groff, the page size for `gtroff' and for output devices are handled
+separately.  *Note Page Layout::, for vertical manipulation of the page
+size.  *Note Line Layout::, for horizontal changes.
 
    A default paper size can be set in the device's `DESC' file.  Most
 output devices also have a command line option `-p' to override the
@@ -850,11 +865,11 @@ page dimensions set in this way (most do).
 
 File: groff,  Node: Invocation Examples,  Prev: Paper Size,  Up: Invoking groff
 
-Invocation Examples
-===================
+2.6 Invocation Examples
+=======================
 
-   This section lists several common uses of `groff' and the
-corresponding command lines.
+This section lists several common uses of `groff' and the corresponding
+command lines.
 
 
      groff file
@@ -901,15 +916,14 @@ in general; for example, to load `trace.tmac', either `-mtrace' or
 
 File: groff,  Node: grog,  Prev: Invocation Examples,  Up: Invocation Examples
 
-`grog'
-------
+2.6.1 `grog'
+------------
 
-   `grog' reads files, guesses which of the `groff' preprocessors
-and/or macro packages are required for formatting them, and prints the
-`groff' command including those options on the standard output.  It
-generates one or more of the options `-e', `-man', `-me', `-mm',
-`-mom', `-ms', `-mdoc', `-mdoc-old', `-p', `-R', `-g', `-G', `-s', and
-`-t'.
+`grog' reads files, guesses which of the `groff' preprocessors and/or
+macro packages are required for formatting them, and prints the `groff'
+command including those options on the standard output.  It generates
+one or more of the options `-e', `-man', `-me', `-mm', `-mom', `-ms',
+`-mdoc', `-mdoc-old', `-p', `-R', `-g', `-G', `-s', and `-t'.
 
    A special file name `-' refers to the standard input.  Specifying no
 files also means to read the standard input.  Any specified options are
@@ -938,10 +952,10 @@ something meaningful (i.e. either a file or a pager program like
 
 File: groff,  Node: Tutorial for Macro Users,  Next: Macro Packages,  Prev: Invoking groff,  Up: Top
 
-Tutorial for Macro Users
-************************
+3 Tutorial for Macro Users
+**************************
 
-   Most users tend to use a macro package to format their papers.  This
+Most users tend to use a macro package to format their papers.  This
 means that the whole breadth of `groff' is not necessary for most
 people.  This chapter covers the material needed to efficiently use a
 macro package.
@@ -954,12 +968,12 @@ macro package.
 
 File: groff,  Node: Basics,  Next: Common Features,  Prev: Tutorial for Macro Users,  Up: Tutorial for Macro Users
 
-Basics
-======
+3.1 Basics
+==========
 
-   This section covers some of the basic concepts necessary to
-understand how to use a macro package.(1) (*note Basics-Footnote-1::)
-References are made throughout to more detailed information, if desired.
+This section covers some of the basic concepts necessary to understand
+how to use a macro package.(1) (*note Basics-Footnote-1::) References
+are made throughout to more detailed information, if desired.
 
    `gtroff' reads an input file prepared by the user and outputs a
 formatted document suitable for publication or framing.  The input
@@ -1089,12 +1103,12 @@ File: groff,  Node: Basics-Footnotes,  Up: Basics
 
 File: groff,  Node: Common Features,  Prev: Basics,  Up: Tutorial for Macro Users
 
-Common Features
-===============
+3.2 Common Features
+===================
 
-   `gtroff' provides very low-level operations for formatting a
-document.  There are many common routine operations which are done in
-all documents.  These common operations are written into "macros" and
+`gtroff' provides very low-level operations for formatting a document.
+There are many common routine operations which are done in all
+documents.  These common operations are written into "macros" and
 collected into a "macro package".
 
    All macro packages provide certain common capabilities which fall
@@ -1120,10 +1134,10 @@ into the following categories.
 
 File: groff,  Node: Paragraphs,  Next: Sections and Chapters,  Prev: Common Features,  Up: Common Features
 
-Paragraphs
-----------
+3.2.1 Paragraphs
+----------------
 
-   One of the most common and most used capability is starting a
+One of the most common and most used capability is starting a
 paragraph.  There are a number of different types of paragraphs, any of
 which can be initiated with macros supplied by the macro package.
 Normally, paragraphs start with a blank line and the first line
@@ -1161,22 +1175,22 @@ at the margin and the remaining text indented.
 
 File: groff,  Node: Sections and Chapters,  Next: Headers and Footers,  Prev: Paragraphs,  Up: Common Features
 
-Sections and Chapters
----------------------
+3.2.2 Sections and Chapters
+---------------------------
 
-   Most macro packages supply some form of section headers.  The
-simplest kind is simply the heading on a line by itself in bold type.
-Others supply automatically numbered section heading or different
-heading styles at different levels.  Some, more sophisticated, macro
-packages supply macros for starting chapters and appendices.
+Most macro packages supply some form of section headers.  The simplest
+kind is simply the heading on a line by itself in bold type.  Others
+supply automatically numbered section heading or different heading
+styles at different levels.  Some, more sophisticated, macro packages
+supply macros for starting chapters and appendices.
 
 
 File: groff,  Node: Headers and Footers,  Next: Page Layout Adjustment,  Prev: Sections and Chapters,  Up: Common Features
 
-Headers and Footers
--------------------
+3.2.3 Headers and Footers
+-------------------------
 
-   Every macro package gives some way to manipulate the "headers" and
+Every macro package gives some way to manipulate the "headers" and
 "footers" (also called "titles") on each page.  This is text put at the
 top and bottom of each page, respectively, which contain data like the
 current page number, the current chapter title, and so on.  Its
@@ -1192,19 +1206,19 @@ with the `%' character (see *Note Page Layout::, for more details).
 
 File: groff,  Node: Page Layout Adjustment,  Next: Displays,  Prev: Headers and Footers,  Up: Common Features
 
-Page Layout
------------
+3.2.4 Page Layout
+-----------------
 
-   Most macro packages let the user specify top and bottom margins and
+Most macro packages let the user specify top and bottom margins and
 other details about the appearance of the printed pages.
 
 
 File: groff,  Node: Displays,  Next: Footnotes and Annotations,  Prev: Page Layout Adjustment,  Up: Common Features
 
-Displays
---------
+3.2.5 Displays
+--------------
 
-   "Displays" are sections of text to be set off from the body of the
+"Displays" are sections of text to be set off from the body of the
 paper.  Major quotes, tables, and figures are types of displays, as are
 all the examples used in this document.
 
@@ -1230,10 +1244,10 @@ surrounding text `flows' around the keep, thus leaving no blank areas.
 
 File: groff,  Node: Footnotes and Annotations,  Next: Table of Contents,  Prev: Displays,  Up: Common Features
 
-Footnotes and Annotations
--------------------------
+3.2.6 Footnotes and Annotations
+-------------------------------
 
-   There are a number of requests to save text for later printing.
+There are a number of requests to save text for later printing.
 
    "Footnotes" are printed at the bottom of the current page.
 
@@ -1248,25 +1262,25 @@ means of automatically numbering either type of annotation.
 
 File: groff,  Node: Table of Contents,  Next: Indices,  Prev: Footnotes and Annotations,  Up: Common Features
 
-Table of Contents
------------------
+3.2.7 Table of Contents
+-----------------------
 
-   "Tables of contents" are a type of delayed text having a tag
-(usually the page number) attached to each entry after a row of dots.
-The table accumulates throughout the paper until printed, usually after
-the paper has ended.  Many macro packages provide the ability to have
-several tables of contents (e.g. a standard table of contents, a list
-of tables, etc).
+"Tables of contents" are a type of delayed text having a tag (usually
+the page number) attached to each entry after a row of dots.  The table
+accumulates throughout the paper until printed, usually after the paper
+has ended.  Many macro packages provide the ability to have several
+tables of contents (e.g. a standard table of contents, a list of
+tables, etc).
 
 
 File: groff,  Node: Indices,  Next: Paper Formats,  Prev: Table of Contents,  Up: Common Features
 
-Indices
--------
+3.2.8 Indices
+-------------
 
-   While some macro packages use the term "index", none actually
-provide that functionality.  The facilities they call indices are
-actually more appropriate for tables of contents.
+While some macro packages use the term "index", none actually provide
+that functionality.  The facilities they call indices are actually more
+appropriate for tables of contents.
 
    To produce a real index in a document, external tools like the
 `makeindex' program are necessary.
@@ -1274,10 +1288,10 @@ actually more appropriate for tables of contents.
 
 File: groff,  Node: Paper Formats,  Next: Multiple Columns,  Prev: Indices,  Up: Common Features
 
-Paper Formats
--------------
+3.2.9 Paper Formats
+-------------------
 
-   Some macro packages provide stock formats for various kinds of
+Some macro packages provide stock formats for various kinds of
 documents.  Many of them provide a common format for the title and
 opening pages of a technical paper.  The `mm' macros in particular
 provide formats for letters and memoranda.
@@ -1285,38 +1299,38 @@ provide formats for letters and memoranda.
 
 File: groff,  Node: Multiple Columns,  Next: Font and Size Changes,  Prev: Paper Formats,  Up: Common Features
 
-Multiple Columns
-----------------
+3.2.10 Multiple Columns
+-----------------------
 
-   Some macro packages (but not `man') provide the ability to have two
-or more columns on a page.
+Some macro packages (but not `man') provide the ability to have two or
+more columns on a page.
 
 
 File: groff,  Node: Font and Size Changes,  Next: Predefined Strings,  Prev: Multiple Columns,  Up: Common Features
 
-Font and Size Changes
----------------------
+3.2.11 Font and Size Changes
+----------------------------
 
-   The built-in font and size functions are not always intuitive, so all
+The built-in font and size functions are not always intuitive, so all
 macro packages provide macros to make these operations simpler.
 
 
 File: groff,  Node: Predefined Strings,  Next: Preprocessor Support,  Prev: Font and Size Changes,  Up: Common Features
 
-Predefined Strings
-------------------
+3.2.12 Predefined Strings
+-------------------------
 
-   Most macro packages provide various predefined strings for a variety
-of uses; examples are sub- and superscripts, printable dates, quotes and
+Most macro packages provide various predefined strings for a variety of
+uses; examples are sub- and superscripts, printable dates, quotes and
 various special characters.
 
 
 File: groff,  Node: Preprocessor Support,  Next: Configuration and Customization,  Prev: Predefined Strings,  Up: Common Features
 
-Preprocessor Support
---------------------
+3.2.13 Preprocessor Support
+---------------------------
 
-   All macro packages provide support for various preprocessors and may
+All macro packages provide support for various preprocessors and may
 extend their functionality.
 
    For example, all macro packages mark tables (which are processed with
@@ -1327,21 +1341,20 @@ new page (when the table is too long to fit on a single page).
 
 File: groff,  Node: Configuration and Customization,  Prev: Preprocessor Support,  Up: Common Features
 
-Configuration and Customization
--------------------------------
+3.2.14 Configuration and Customization
+--------------------------------------
 
-   Some macro packages provide means of customizing many of the details
-of how the package behaves.  This ranges from setting the default type
-size to changing the appearance of section headers.
+Some macro packages provide means of customizing many of the details of
+how the package behaves.  This ranges from setting the default type size
+to changing the appearance of section headers.
 
 
 File: groff,  Node: Macro Packages,  Next: gtroff Reference,  Prev: Tutorial for Macro Users,  Up: Top
 
-Macro Packages
-**************
+4 Macro Packages
+****************
 
-   This chapter documents the main macro packages that come with
-`groff'.
+This chapter documents the main macro packages that come with `groff'.
 
    Different main macro packages can't be used at the same time; for
 example
@@ -1366,12 +1379,12 @@ non-option arguments; the above (failing) sample is thus reordered to
 
 File: groff,  Node: man,  Next: mdoc,  Prev: Macro Packages,  Up: Macro Packages
 
-`man'
-=====
+4.1 `man'
+=========
 
-   This is the most popular and probably the most important macro
-package of `groff'.  It is easy to use, and a vast majority of manual
-pages are based on it.
+This is the most popular and probably the most important macro package
+of `groff'.  It is easy to use, and a vast majority of manual pages are
+based on it.
 
 * Menu:
 
@@ -1383,3 +1396,7300 @@ pages are based on it.
 * Preprocessors in man pages::
 * Optional man extensions::
 
+
+File: groff,  Node: Man options,  Next: Man usage,  Prev: man,  Up: man
+
+4.1.1 Options
+-------------
+
+The command line format for using the `man' macros with `groff' is:
+
+
+     groff -m man [ -rLL=LENGTH ] [ -rLT=LENGTH ] [ -rFT=DIST ]
+           [ -rcR=1 ] [ -rC1 ] [ -rD1 ] [-rHY=FLAGS ]
+           [ -rPNNN ] [ -rSXX ] [ -rXNNN ]
+           [ -rIN=LENGTH ] [ -rSN=LENGTH ] [ FILES... ]
+
+It is possible to use `-man' instead of `-m man'.
+
+`-rcR=1'
+     This option (the default if a TTY output device is used) creates a
+     single, very long page instead of multiple pages.  Use `-rcR=0' to
+     disable it.
+
+`-rC1'
+     If more than one manual page is given on the command line, number
+     the pages continuously, rather than starting each at 1.
+
+`-rD1'
+     Double-sided printing.  Footers for even and odd pages are
+     formatted differently.
+
+`-rFT=DIST'
+     Set the position of the footer text to DIST.  If positive, the
+     distance is measured relative to the top of the page, otherwise it
+     is relative to the bottom.  The default is -0.5i.
+
+`-rHY=FLAGS'
+     Set hyphenation flags.  Possible values are 1 to hyphenate without
+     restrictions, 2  to not hyphenate the last word on a page, 4 to
+     not hyphenate the last two characters of a word, and 8 to not
+     hyphenate the first two characters of a word.  These values are
+     additive; the default is 14.
+
+`-rIN=LENGTH'
+     Set the body text indentation to LENGTH.  If not specified, the
+     indentation defaults to 7n (7 characters) in nroff mode and 7.2n
+     otherwise.  For nroff, this value should always be an integer
+     multiple of unit `n' to get consistent indentation.
+
+`-rLL=LENGTH'
+     Set line length to LENGTH.  If not specified, the line length is
+     set to respect any value set by a prior `ll' request (which _must_
+     be in effect when the `TH' macro is invoked), if this differs from
+     the built-in default for the formatter; otherwise it defaults to
+     78n in nroff mode (this is 78 characters per line) and 6.5i in
+     troff mode.(1) (*note Man options-Footnote-1::)
+
+`-rLT=LENGTH'
+     Set title length to LENGTH.  If not specified, the title length
+     defaults to the line length.
+
+`-rPNNN'
+     Page numbering starts with NNN rather than with 1.
+
+`-rSXX'
+     Use XX (which can be 10, 11, or 12pt) as the base document font
+     size instead of the default value of 10pt.
+
+`-rSN=LENGTH'
+     Set the indentation for sub-subheadings to LENGTH.  If not
+     specified, the indentation defaults to 3n.
+
+`-rXNNN'
+     After page NNN, number pages as NNNa, NNNb, NNNc, etc.  For
+     example, the option `-rX2' produces the following page numbers: 1,
+     2, 2a, 2b, 2c, etc.
+
+
+File: groff,  Node: Man options-Footnotes,  Up: Man options
+
+   (1) Note that the use of a `.ll LENGTH' request to initialize the
+line length, prior to use of the `TH' macro, is supported for backward
+compatibility with some versions of the `man' program.  _Always_ use the
+`-rLL=LENGTH' option, or an equivalent `.nr LL LENGTH' request, in
+preference to such a `.ll LENGTH' request.  In particular, note that in
+nroff mode, the request `.ll 65n', (with any LENGTH expression which
+evaluates equal to 65n, i.e., the formatter's default line length in
+nroff mode), will _not_ set the line length to 65n (it will be adjusted
+to the `man' macro package's default setting of 78n), whereas the use
+of the `-rLL=65n' option, or the `.nr LL 65n' request _will_ establish
+a line length of 65n.
+
+
+File: groff,  Node: Man usage,  Next: Man font macros,  Prev: Man options,  Up: man
+
+4.1.2 Usage
+-----------
+
+This section describes the available macros for manual pages.  For
+further customization, put additional macros and requests into the file
+`man.local' which is loaded immediately after the `man' package.
+
+ -- Macro: .TH title section [extra1 [extra2 [extra3]]]
+     Set the title of the man page to TITLE and the section to SECTION,
+     which must have a value between 1 and 8.  The value of SECTION may
+     also have a string appended, e.g. `.pm', to indicate a specific
+     subsection of the man pages.
+
+     Both TITLE and SECTION are positioned at the left and right in the
+     header line (with SECTION in parentheses immediately appended to
+     TITLE.  EXTRA1 is positioned in the middle of the footer line.
+     EXTRA2 is positioned at the left in the footer line (or at the
+     left on even pages and at the right on odd pages if double-sided
+     printing is active).  EXTRA3 is centered in the header line.
+
+     For HTML output, headers and footers are completely suppressed.
+
+     Additionally, this macro starts a new page; the new line number
+     is 1 again (except if the `-rC1' option is given on the command
+     line) - this feature is intended only for formatting multiple man
+     pages; a single man page should contain exactly one `TH' macro at
+     the beginning of the file.
+
+ -- Macro: .SH [heading]
+     Set up an unnumbered section heading sticking out to the left.
+     Prints out all the text following `SH' up to the end of the line
+     (or the text in the next line if there is no argument to `SH') in
+     bold face (or the font specified by the string `HF'), one size
+     larger than the base document size.  Additionally, the left margin
+     and the indentation for the following text is reset to its default
+     value.
+
+ -- Macro: .SS [heading]
+     Set up an unnumbered (sub)section heading.  Prints out all the text
+     following `SS' up to the end of the line (or the text in the next
+     line if there is no argument to `SS') in bold face (or the font
+     specified by the string `HF'), at the same size as the base
+     document size.  Additionally, the left margin and the indentation
+     for the following text is reset to its default value.
+
+ -- Macro: .TP [nnn]
+     Set up an indented paragraph with label.  The indentation is set to
+     NNN if that argument is supplied (the default unit is `n' if
+     omitted), otherwise it is set to the previous indentation value
+     specified with `TP', `IP', or `HP' (or to the default value if
+     none of them have been used yet).
+
+     The first line of text following this macro is interpreted as a
+     string to be printed flush-left, as it is appropriate for a label.
+     It is not interpreted as part of a paragraph, so there is no
+     attempt to fill the first line with text from the following input
+     lines.  Nevertheless, if the label is not as wide as the
+     indentation the paragraph starts at the same line (but indented),
+     continuing on the following lines.  If the label is wider than the
+     indentation the descriptive part of the paragraph begins on the
+     line following the label, entirely indented.  Note that neither
+     font shape nor font size of the label is set to a default value;
+     on the other hand, the rest of the text has default font settings.
+
+ -- Macro: .LP
+ -- Macro: .PP
+ -- Macro: .P
+     These macros are mutual aliases.  Any of them causes a line break
+     at the current position, followed by a vertical space downwards by
+     the amount specified by the `PD' macro.  The font size and shape
+     are reset to the default value (10pt roman if no `-rS' option is
+     given on the command line).  Finally, the current left margin and
+     the indentation is restored.
+
+ -- Macro: .IP [designator [nnn]]
+     Set up an indented paragraph, using DESIGNATOR as a tag to mark
+     its beginning.  The indentation is set to NNN if that argument is
+     supplied (default unit is `n'), otherwise it is set to the
+     previous indentation value specified with `TP', `IP', or `HP' (or
+     the default value if none of them have been used yet).  Font size
+     and face of the paragraph (but not the designator) are reset to
+     their default values.
+
+     To start an indented paragraph with a particular indentation but
+     without a designator, use `""' (two double quotes) as the first
+     argument of `IP'.
+
+     For example, to start a paragraph with bullets as the designator
+     and 4 en indentation, write
+
+
+          .IP \(bu 4
+
+
+ -- Macro: .HP [nnn]
+     Set up a paragraph with hanging left indentation.  The indentation
+     is set to NNN if that argument is supplied (default unit is `n'),
+     otherwise it is set to the previous indentation value specified
+     with `TP', `IP', or `HP' (or the default value if non of them have
+     been used yet).  Font size and face are reset to their default
+     values.
+
+ -- Macro: .RS [nnn]
+     Move the left margin to the right by the value NNN if specified
+     (default unit is `n'); otherwise it is set to the previous
+     indentation value specified with `TP', `IP', or `HP' (or to the
+     default value if none of them have been used yet).  The
+     indentation value is then set to the default.
+
+     Calls to the `RS' macro can be nested.
+
+ -- Macro: .RE [nnn]
+     Move the left margin back to level NNN, restoring the previous left
+     margin.  If no argument is given, it moves one level back.  The
+     first level (i.e., no call to `RS' yet) has number 1, and each call
+     to `RS' increases the level by 1.
+
+   To summarize, the following macros cause a line break with the
+insertion of vertical space (which amount can be changed with the `PD'
+macro): `SH', `SS', `TP', `LP' (`PP', `P'), `IP', and `HP'.
+
+   The macros `RS' and `RE' also cause a break but do not insert
+vertical space.
+
+   Finally, the macros `SH', `SS', `LP' (`PP', `P'), and `RS' reset the
+indentation to its default value.
+
+
+File: groff,  Node: Man font macros,  Next: Miscellaneous man macros,  Prev: Man usage,  Up: man
+
+4.1.3 Macros to set fonts
+-------------------------
+
+The standard font is roman; the default text size is 10 point.  If
+command line option `-rS=N' is given, use Npt as the default text size.
+
+ -- Macro: .SM [text]
+     Set the text on the same line or the text on the next line in a
+     font that is one point size smaller than the default font.
+
+ -- Macro: .SB [text]
+     Set the text on the same line or the text on the next line in bold
+     face font, one point size smaller than the default font.
+
+ -- Macro: .BI text
+     Set its arguments alternately in bold face and italic, without a
+     space between the arguments.  Thus,
+
+
+          .BI this "word and" that
+
+     produces "thisword andthat" with "this" and "that" in bold face,
+     and "word and" in italics.
+
+ -- Macro: .IB text
+     Set its arguments alternately in italic and bold face, without a
+     space between the arguments.
+
+ -- Macro: .RI text
+     Set its arguments alternately in roman and italic, without a space
+     between the arguments.
+
+ -- Macro: .IR text
+     Set its arguments alternately in italic and roman, without a space
+     between the arguments.
+
+ -- Macro: .BR text
+     Set its arguments alternately in bold face and roman, without a
+     space between the arguments.
+
+ -- Macro: .RB text
+     Set its arguments alternately in roman and bold face, without a
+     space between the arguments.
+
+ -- Macro: .B [text]
+     Set TEXT in bold face.  If no text is present on the line where
+     the macro is called, then the text of the next line appears in bold
+     face.
+
+ -- Macro: .I [text]
+     Set TEXT in italic.  If no text is present on the line where the
+     macro is called, then the text of the next line appears in italic.
+
+
+File: groff,  Node: Miscellaneous man macros,  Next: Predefined man strings,  Prev: Man font macros,  Up: man
+
+4.1.4 Miscellaneous macros
+--------------------------
+
+The default indentation is 7.2n in troff mode and 7n in nroff mode
+except for `grohtml' which ignores indentation.
+
+ -- Macro: .DT
+     Set tabs every 0.5 inches.  Since this macro is always executed
+     during a call to the `TH' macro, it makes sense to call it only if
+     the tab positions have been changed.
+
+ -- Macro: .PD [nnn]
+     Adjust the empty space before a new paragraph (or section).  The
+     optional argument gives the amount of space (default unit is `v');
+     without parameter, the value is reset to its default value (1 line
+     in nroff mode, 0.4v otherwise).
+
+     This affects the macros `SH', `SS', `TP', `LP' (as well as `PP'
+     and `P'), `IP', and `HP'.
+
+   The following two macros are included for BSD compatibility.
+
+ -- Macro: .AT [system [release]]
+     Alter the footer for use with AT&T manpages.  This command exists
+     only for compatibility; don't use it.  The first argument SYSTEM
+     can be:
+
+    `3'
+          7th Edition (the default)
+
+    `4'
+          System III
+
+    `5'
+          System V
+
+     An optional second argument RELEASE to `AT' specifies the release
+     number (such as "System V Release 3").
+
+ -- Macro: .UC [version]
+     Alters the footer for use with BSD manpages.  This command exists
+     only for compatibility; don't use it.  The argument can be:
+
+    `3'
+          3rd Berkeley Distribution (the default)
+
+    `4'
+          4th Berkeley Distribution
+
+    `5'
+          4.2 Berkeley Distribution
+
+    `6'
+          4.3 Berkeley Distribution
+
+    `7'
+          4.4 Berkeley Distribution
+
+
+File: groff,  Node: Predefined man strings,  Next: Preprocessors in man pages,  Prev: Miscellaneous man macros,  Up: man
+
+4.1.5 Predefined strings
+------------------------
+
+The following strings are defined:
+
+ -- String: \*[S]
+     Switch back to the default font size.
+
+ -- String: \*[HF]
+     The typeface used for headings.  The default is `B'.
+
+ -- String: \*[R]
+     The `registered' sign.
+
+ -- String: \*[Tm]
+     The `trademark' sign.
+
+ -- String: \*[lq]
+ -- String: \*[rq]
+     Left and right quote.  This is equal to `\(lq' and `\(rq',
+     respectively.
+
+
+File: groff,  Node: Preprocessors in man pages,  Next: Optional man extensions,  Prev: Predefined man strings,  Up: man
+
+4.1.6 Preprocessors in `man' pages
+----------------------------------
+
+If a preprocessor like `gtbl' or `geqn' is needed, it has become common
+usage to make the first line of the man page look like this:
+
+
+     '\" WORD
+
+Note the single space character after the double quote.  WORD consists
+of letters for the needed preprocessors: `e' for `geqn', `r' for
+`grefer', `t' for `gtbl'.  Modern implementations of the `man' program
+read this first line and automatically call the right preprocessor(s).
+
+
+File: groff,  Node: Optional man extensions,  Prev: Preprocessors in man pages,  Up: man
+
+4.1.7 Optional `man' extensions
+-------------------------------
+
+Use the file `man.local' for local extensions to the `man' macros or
+for style changes.
+
+Custom headers and footers
+..........................
+
+In groff versions 1.18.2 and later, you can specify custom headers and
+footers by redefining the following macros in `man.local'.
+
+ -- Macro: .PT
+     Control the content of the headers.  Normally, the header prints
+     the command name and section number on either side, and the
+     optional fifth argument to `TH' in the center.
+
+ -- Macro: .BT
+     Control the content of the footers.  Normally, the footer prints
+     the page number and the third and fourth arguments to `TH'.
+
+     Use the `FT' number register to specify the footer position.  The
+     default is -0.5i.
+
+Ultrix-specific man macros
+..........................
+
+The `groff' source distribution includes a file named `man.ultrix',
+containing macros compatible with the Ultrix variant of `man'.  Copy
+this file into `man.local' (or use the `mso' request to load it) to
+enable the following macros.
+
+ -- Macro: .CT key
+     Print `<CTRL/KEY>'.
+
+ -- Macro: .CW
+     Print subsequent text using the constant width (Courier) typeface.
+
+ -- Macro: .Ds
+     Begin a non-filled display.
+
+ -- Macro: .De
+     End a non-filled display started with `Ds'.
+
+ -- Macro: .EX [indent]
+     Begins a non-filled display using the constant width (Courier)
+     typeface.  Use the optional INDENT argument to indent the display.
+
+ -- Macro: .EE
+     End a non-filled display started with `EX'.
+
+ -- Macro: .G [text]
+     Sets TEXT in Helvetica.  If no text is present on the line where
+     the macro is called, then the text of the next line appears in
+     Helvetica.
+
+ -- Macro: .GL [text]
+     Sets TEXT in Helvetica Oblique.  If no text is present on the line
+     where the macro is called, then the text of the next line appears
+     in Helvetica Oblique.
+
+ -- Macro: .HB [text]
+     Sets TEXT in Helvetica Bold.  If no text is present on the line
+     where the macro is called, then all text up to the next `HB'
+     appears in Helvetica Bold.
+
+ -- Macro: .TB [text]
+     Identical to `HB'.
+
+ -- Macro: .MS title sect [punct]
+     Set a manpage reference in Ultrix format.  The TITLE is in Courier
+     instead of italic.  Optional punctuation follows the section
+     number without an intervening space.
+
+ -- Macro: .NT [`C'] [title]
+     Begin a note.  Print the optional title, or the word "Note",
+     centered on the page.  Text following the macro makes up the body
+     of the note, and is indented on both sides.  If the first argument
+     is `C', the body of the note is printed centered (the second
+     argument replaces the word "Note" if specified).
+
+ -- Macro: .NE
+     End a note begun with `NT'.
+
+ -- Macro: .PN path [punct]
+     Set the path name in constant width (Courier), followed by
+     optional punctuation.
+
+ -- Macro: .Pn [punct] path [punct]
+     When called with two arguments, identical to `PN'.  When called
+     with three arguments, set the second argument in constant width
+     (Courier), bracketed by the first and third arguments in the
+     current font.
+
+ -- Macro: .R
+     Switch to roman font and turn off any underlining in effect.
+
+ -- Macro: .RN
+     Print the string `<RETURN>'.
+
+ -- Macro: .VS [`4']
+     Start printing a change bar in the margin if the number `4' is
+     specified.  Otherwise, this macro does nothing.
+
+ -- Macro: .VE
+     End printing the change bar begun by `VS'.
+
+Simple example
+..............
+
+The following example `man.local' file alters the `SH' macro to add
+some extra vertical space before printing the heading.  Headings are
+printed in Helvetica Bold.
+
+
+     .\" Make the heading fonts Helvetica
+     .ds HF HB
+     .
+     .\" Put more whitespace in front of headings.
+     .rn SH SH-orig
+     .de SH
+     .  if t .sp (u;\\n[PD]*2)
+     .  SH-orig \\$*
+     ..
+
+
+File: groff,  Node: mdoc,  Next: ms,  Prev: man,  Up: Macro Packages
+
+4.2 `mdoc'
+==========
+
+See the `groff_mdoc(7)' man page (type `man groff_mdoc' at the command
+line).
+
+
+File: groff,  Node: ms,  Next: me,  Prev: mdoc,  Up: Macro Packages
+
+4.3 `ms'
+========
+
+The `-ms' macros are suitable for reports, letters, books, user
+manuals, and so forth.  The package provides macros for cover pages,
+section headings, paragraphs, lists, footnotes, pagination, and a table
+of contents.
+
+* Menu:
+
+* ms Intro::
+* General ms Structure::
+* ms Document Control Registers::
+* ms Cover Page Macros::
+* ms Body Text::
+* ms Page Layout::
+* Differences from AT&T ms::
+* Naming Conventions::
+
+
+File: groff,  Node: ms Intro,  Next: General ms Structure,  Prev: ms,  Up: ms
+
+4.3.1 Introduction to `ms'
+--------------------------
+
+The original `-ms' macros were included with AT&T `troff' as well as
+the `man' macros.  While the `man' package is intended for brief
+documents that can be read on-line as well as printed, the `ms' macros
+are suitable for longer documents that are meant to be printed rather
+than read on-line.
+
+   The `ms' macro package included with `groff' is a complete,
+bottom-up re-implementation.  Several macros (specific to AT&T or
+Berkeley) are not included, while several new commands are.  *Note
+Differences from AT&T ms::, for more information.
+
+
+File: groff,  Node: General ms Structure,  Next: ms Document Control Registers,  Prev: ms Intro,  Up: ms
+
+4.3.2 General structure of an `ms' document
+-------------------------------------------
+
+The `ms' macro package expects a certain amount of structure, but not
+as much as packages such as `man' or `mdoc'.
+
+   The simplest documents can begin with a paragraph macro (such as
+`LP' or `PP'), and consist of text separated by paragraph macros or
+even blank lines.  Longer documents have a structure as follows:
+
+*Document type*
+     If you invoke the `RP' (report) macro on the first line of the
+     document, `groff' prints the cover page information on its own
+     page; otherwise it prints the information on the first page with
+     your document text immediately following.  Other document formats
+     found in AT&T `troff' are specific to AT&T or Berkeley, and are
+     not supported in `groff'.
+
+*Format and layout*
+     By setting number registers, you can change your document's type
+     (font and size), margins, spacing, headers and footers, and
+     footnotes.  *Note ms Document Control Registers::, for more
+     details.
+
+*Cover page*
+     A cover page consists of a title, the author's name and
+     institution, an abstract, and the date.(1) (*note General ms
+     Structure-Footnote-1::)  *Note ms Cover Page Macros::, for more
+     details.
+
+*Body*
+     Following the cover page is your document.  You can use the `ms'
+     macros to write reports, letters, books, and so forth.  The
+     package is designed for structured documents, consisting of
+     paragraphs interspersed with headings and augmented by lists,
+     footnotes, tables, and other common constructs.  *Note ms Body
+     Text::, for more details.
+
+*Table of contents*
+     Longer documents usually include a table of contents, which you can
+     invoke by placing the `TC' macro at the end of your document.  The
+     `ms' macros have minimal indexing facilities, consisting of the
+     `IX' macro, which prints an entry on standard error.  Printing the
+     table of contents at the end is necessary since `groff' is a
+     single-pass text formatter, thus it cannot determine the page
+     number of each section until that section has actually been set
+     and printed.  Since `ms' output is intended for hardcopy, you can
+     manually relocate the pages containing the table of contents
+     between the cover page and the body text after printing.
+
+
+File: groff,  Node: General ms Structure-Footnotes,  Up: General ms Structure
+
+   (1) Actually, only the title is required.
+
+
+File: groff,  Node: ms Document Control Registers,  Next: ms Cover Page Macros,  Prev: General ms Structure,  Up: ms
+
+4.3.3 Document control registers
+--------------------------------
+
+The following is a list of document control number registers.  For the
+sake of consistency, set registers related to margins at the beginning
+of your document, or just after the `RP' macro.  You can set other
+registers later in your document, but you should keep them together at
+the beginning to make them easy to find and edit as necessary.
+
+Margin Settings
+...............
+
+ -- Register: \n[PO]
+     Defines the page offset (i.e., the left margin).  There is no
+     explicit right margin setting; the combination of the `PO' and `LL'
+     registers implicitly define the right margin width.
+
+     Effective: next page.
+
+     Default value: 1i.
+
+ -- Register: \n[LL]
+     Defines the line length (i.e., the width of the body text).
+
+     Effective: next paragraph.
+
+     Default: 6i.
+
+ -- Register: \n[LT]
+     Defines the title length (i.e., the header and footer width).  This
+     is usually the same as `LL', but not necessarily.
+
+     Effective: next paragraph.
+
+     Default: 6i.
+
+ -- Register: \n[HM]
+     Defines the header margin height at the top of the page.
+
+     Effective: next page.
+
+     Default: 1i.
+
+ -- Register: \n[FM]
+     Defines the footer margin height at the bottom of the page.
+
+     Effective: next page.
+
+     Default: 1i.
+
+Text Settings
+.............
+
+ -- Register: \n[PS]
+     Defines the point size of the body text.  If the value is larger
+     than or equal to 1000, divide it by 1000 to get a fractional point
+     size.  For example, `.nr PS 10250' sets the document's point size
+     to 10.25p.
+
+     Effective: next paragraph.
+
+     Default: 10p.
+
+ -- Register: \n[VS]
+     Defines the space between lines (line height plus leading).  If the
+     value is larger than or equal to 1000, divide it by 1000 to get a
+     fractional point size.  Due to backwards compatibility, `VS' must
+     be smaller than 40000 (this is 40.0p).
+
+     Effective: next paragraph.
+
+     Default: 12p.
+
+ -- Register: \n[PSINCR]
+     Defines an increment in point size, which will be applied to
+     section headings at nesting levels below the value specified in
+     `GROWPS'.  The value of `PSINCR' should be specified in points,
+     with the p scaling factor, and may include a fractional component;
+     for example, `.nr PSINCR 1.5p' sets a point size increment of 1.5p.
+
+     Effective: next section heading.
+
+     Default: 1p.
+
+ -- Register: \n[GROWPS]
+     Defines the heading level below which the point size increment set
+     by `PSINCR' becomes effective.  Section headings at and above the
+     level specified by `GROWPS' will be printed at the point size set
+     by `PS'; for each level below the value of `GROWPS', the point
+     size will be increased in steps equal to the value of `PSINCR'.
+     Setting `GROWPS' to any value less than 2 disables the incremental
+     heading size feature.
+
+     Effective: next section heading.
+
+     Default: 0.
+
+ -- Register: \n[HY]
+     Defines the hyphenation level.  `HY' sets safely the value of the
+     low-level `hy' register.  Setting the value of `HY' to 0 is
+     equivalent to using the `nh' request.
+
+     Effective: next paragraph.
+
+     Default: 14.
+
+ -- Register: \n[FAM]
+     Defines the font family used to typeset the document.
+
+     Effective: next paragraph.
+
+     Default: as defined in the output device.
+
+Paragraph Settings
+..................
+
+ -- Register: \n[PI]
+     Defines the initial indentation of a (`PP' macro) paragraph.
+
+     Effective: next paragraph.
+
+     Default: 5n.
+
+ -- Register: \n[PD]
+     Defines the space between paragraphs.
+
+     Effective: next paragraph.
+
+     Default: 0.3v.
+
+ -- Register: \n[QI]
+     Defines the indentation on both sides of a quoted (`QP' macro)
+     paragraph.
+
+     Effective: next paragraph.
+
+     Default: 5n.
+
+ -- Register: \n[PORPHANS]
+     Defines the minimum number of initial lines of any paragraph which
+     should be kept together, to avoid orphan lines at the bottom of a
+     page.  If a new paragraph is started close to the bottom of a page,
+     and there is insufficient space to accommodate `PORPHANS' lines
+     before an automatic page break, then the page break will be forced,
+     before the start of the paragraph.
+
+     Effective: next paragraph.
+
+     Default: 1.
+
+ -- Register: \n[HORPHANS]
+     Defines the minimum number of lines of the following paragraph
+     which should be kept together with any section heading introduced
+     by the `NH' or `SH' macros.  If a section heading is placed close
+     to the bottom of a page, and there is insufficient space to
+     accommodate both the heading and at least `HORPHANS' lines of the
+     following paragraph, before an automatic page break, then the page
+     break will be forced before the heading.
+
+     Effective: next paragraph.
+
+     Default: 1.
+
+Footnote Settings
+.................
+
+ -- Register: \n[FL]
+     Defines the length of a footnote.
+
+     Effective: next footnote.
+
+     Default: `\n[LL]' * 5 / 6.
+
+ -- Register: \n[FI]
+     Defines the footnote indentation.
+
+     Effective: next footnote.
+
+     Default: 2n.
+
+ -- Register: \n[FF]
+     The footnote format:
+    `0'
+          Print the footnote number as a superscript; indent the
+          footnote (default).
+
+    `1'
+          Print the number followed by a period (like 1.) and indent the
+          footnote.
+
+    `2'
+          Like 1, without an indentation.
+
+    `3'
+          Like 1, but print the footnote number as a hanging paragraph.
+
+     Effective: next footnote.
+
+     Default: 0.
+
+ -- Register: \n[FPS]
+     Defines the footnote point size.  If the value is larger than or
+     equal to 1000, divide it by 1000 to get a fractional point size.
+
+     Effective: next footnote.
+
+     Default: `\n[PS]' - 2.
+
+ -- Register: \n[FVS]
+     Defines the footnote vertical spacing.  If the value is larger
+     than or equal to 1000, divide it by 1000 to get a fractional point
+     size.
+
+     Effective: next footnote.
+
+     Default: `\n[FPS]' + 2.
+
+ -- Register: \n[FPD]
+     Defines the footnote paragraph spacing.
+
+     Effective: next footnote.
+
+     Default: `\n[PD]' / 2.
+
+Miscellaneous Number Registers
+..............................
+
+ -- Register: \n[MINGW]
+     Defines the minimum width between columns in a multi-column
+     document.
+
+     Effective: next page.
+
+     Default: 2n.
+
+
+File: groff,  Node: ms Cover Page Macros,  Next: ms Body Text,  Prev: ms Document Control Registers,  Up: ms
+
+4.3.4 Cover page macros
+-----------------------
+
+Use the following macros to create a cover page for your document in
+the order shown.
+
+ -- Macro: .RP [`no']
+     Specifies the report format for your document.  The report format
+     creates a separate cover page.  The default action (no `RP' macro)
+     is to print a subset of the cover page on page 1 of your document.
+
+     If you use the word `no' as an optional argument, `groff' prints a
+     title page but does not repeat any of the title page information
+     (title, author, abstract, etc.) on page 1 of the document.
+
+ -- Macro: .P1
+     (P-one) Prints the header on page 1.  The default is to suppress
+     the header.
+
+ -- Macro: .DA [...]
+     (optional) Prints the current date, or the arguments to the macro
+     if any, on the title page (if specified) and in the footers.  This
+     is the default for `nroff'.
+
+ -- Macro: .ND [...]
+     (optional) Prints the current date, or the arguments to the macro
+     if any, on the title page (if specified) but not in the footers.
+     This is the default for `troff'.
+
+ -- Macro: .TL
+     Specifies the document title.  `groff' collects text following the
+     `TL' macro into the title, until reaching the author name or
+     abstract.
+
+ -- Macro: .AU
+     Specifies the author's name, which appears on the line (or lines)
+     immediately following.  You can specify multiple authors as
+     follows:
+
+
+          .AU
+          John Doe
+          .AI
+          University of West Bumblefuzz
+          .AU
+          Martha Buck
+          .AI
+          Monolithic Corporation
+
+          ...
+
+
+ -- Macro: .AI
+     Specifies the author's institution.  You can specify multiple
+     institutions in the same way that you specify multiple authors.
+
+ -- Macro: .AB [`no']
+     Begins the abstract.  The default is to print the word ABSTRACT,
+     centered and in italics, above the text of the abstract.  The word
+     `no' as an optional argument suppresses this heading.
+
+ -- Macro: .AE
+     Ends the abstract.
+
+   The following is example mark-up for a title page.  
+
+
+     .RP
+     .TL
+     The Inevitability of Code Bloat
+     in Commercial and Free Software
+     .AU
+     J. Random Luser
+     .AI
+     University of West Bumblefuzz
+     .AB
+     This report examines the long-term growth
+     of the code bases in two large, popular software
+     packages; the free Emacs and the commercial
+     Microsoft Word.
+     While differences appear in the type or order
+     of features added, due to the different
+     methodologies used, the results are the same
+     in the end.
+     .PP
+     The free software approach is shown to be
+     superior in that while free software can
+     become as bloated as commercial offerings,
+     free software tends to have fewer serious
+     bugs and the added features are in line with
+     user demand.
+     .AE
+
+     ... the rest of the paper follows ...
+
+
+File: groff,  Node: ms Body Text,  Next: ms Page Layout,  Prev: ms Cover Page Macros,  Up: ms
+
+4.3.5 Body text
+---------------
+
+This section describes macros used to mark up the body of your
+document.  Examples include paragraphs, sections, and other groups.
+
+* Menu:
+
+* Paragraphs in ms::
+* Headings in ms::
+* Highlighting in ms::
+* Lists in ms::
+* Indentation values in ms::
+* Tabstops in ms::
+* ms Displays and Keeps::
+* ms Insertions::
+* Example multi-page table::
+* ms Footnotes::
+
+
+File: groff,  Node: Paragraphs in ms,  Next: Headings in ms,  Prev: ms Body Text,  Up: ms Body Text
+
+4.3.5.1 Paragraphs
+..................
+
+The following paragraph types are available.
+
+ -- Macro: .PP
+ -- Macro: .LP
+     Sets a paragraph with an initial indentation.
+
+ -- Macro: .QP
+     Sets a paragraph that is indented at both left and right margins.
+     The effect is identical to the HTML `<BLOCKQUOTE>' element.  The
+     next paragraph or heading returns margins to normal.
+
+ -- Macro: .XP
+     Sets a paragraph whose lines are indented, except for the first
+     line.  This is a Berkeley extension.
+
+   The following markup uses all four paragraph macros.
+
+
+     .NH 2
+     Cases used in the study
+     .LP
+     The following software and versions were
+     considered for this report.
+     .PP
+     For commercial software, we chose
+     .B "Microsoft Word for Windows" ,
+     starting with version 1.0 through the
+     current version (Word 2000).
+     .PP
+     For free software, we chose
+     .B Emacs ,
+     from its first appearance as a standalone
+     editor through the current version (v20).
+     See [Bloggs 2002] for details.
+     .QP
+     Franklin's Law applied to software:
+     software expands to outgrow both
+     RAM and disk space over time.
+     .LP
+     Bibliography:
+     .XP
+     Bloggs, Joseph R.,
+     .I "Everyone's a Critic" ,
+     Underground Press, March 2002.
+     A definitive work that answers all questions
+     and criticisms about the quality and usability of
+     free software.
+
+   The `PORPHANS' register (*note ms Document Control Registers::)
+operates in conjunction with each of these macros, to inhibit the
+printing of orphan lines at the bottom of any page.
+
+
+File: groff,  Node: Headings in ms,  Next: Highlighting in ms,  Prev: Paragraphs in ms,  Up: ms Body Text
+
+4.3.5.2 Headings
+................
+
+Use headings to create a hierarchical structure for your document.  The
+`ms' macros print headings in *bold*, using the same font family and
+point size as the body text.
+
+   The following describes the heading macros:
+
+ -- Macro: .NH curr-level
+ -- Macro: .NH S level0 ...
+     Numbered heading.  The argument is either a numeric argument to
+     indicate the level of the heading, or the letter `S' followed by
+     numeric arguments to set the heading level explicitly.
+
+     If you specify heading levels out of sequence, such as invoking
+     `.NH 3' after `.NH 1', `groff' prints a warning on standard error.
+
+ -- String: \*[SN]
+ -- String: \*[SN-DOT]
+ -- String: \*[SN-NO-DOT]
+     After invocation of `NH', the assigned section number is made
+     available in the strings `SN-DOT' (exactly as it appears in the
+     printed section heading) and `SN-NO-DOT' (with the final period
+     omitted).  The string `SN' is also defined, as an alias for
+     `SN-DOT'; if preferred, you may redefine it as an alias for
+     `SN-NO-DOT', by including the initialization
+
+
+          .ds SN-NO-DOT
+          .als SN SN-NO-DOT
+
+     *before* your first use of `NH', or simply
+
+
+          .als SN SN-NO-DOT
+
+     *after* your first use of `NH'.
+
+ -- Macro: .SH [match-level]
+     Unnumbered subheading.
+
+     The optional MATCH-LEVEL argument is a GNU extension.  It is a
+     number indicating the level of the heading, in a manner analogous
+     to the CURR-LEVEL argument to `.NH'.  Its purpose is to match the
+     point size, at which the heading is printed, to the size of a
+     numbered heading at the same level, when the `GROWPS' and `PSINCR'
+     heading size adjustment mechanism is in effect.  *Note ms Document
+     Control Registers::.
+
+   The `HORPHANS' register (*note ms Document Control Registers::)
+operates in conjunction with the `NH' and `SH' macros, to inhibit the
+printing of orphaned section headings at the bottom of any page.
+
+
+File: groff,  Node: Highlighting in ms,  Next: Lists in ms,  Prev: Headings in ms,  Up: ms Body Text
+
+4.3.5.3 Highlighting
+....................
+
+The `ms' macros provide a variety of methods to highlight or emphasize
+text:
+
+ -- Macro: .B [txt [post [pre]]]
+     Sets its first argument in *bold type*.  If you specify a second
+     argument, `groff' prints it in the previous font after the bold
+     text, with no intervening space (this allows you to set
+     punctuation after the highlighted text without highlighting the
+     punctuation).  Similarly, it prints the third argument (if any) in
+     the previous font *before* the first argument.  For example,
+
+
+          .B foo ) (
+
+     prints (*foo*).
+
+     If you give this macro no arguments, `groff' prints all text
+     following in bold until the next highlighting, paragraph, or
+     heading macro.
+
+ -- Macro: .R [txt [post [pre]]]
+     Sets its first argument in roman (or regular) type.  It operates
+     similarly to the `B' macro otherwise.
+
+ -- Macro: .I [txt [post [pre]]]
+     Sets its first argument in _italic type_.  It operates similarly
+     to the `B' macro otherwise.
+
+ -- Macro: .CW [txt [post [pre]]]
+     Sets its first argument in a `constant width face'.  It operates
+     similarly to the `B' macro otherwise.
+
+ -- Macro: .BI [txt [post [pre]]]
+     Sets its first argument in bold italic type.  It operates
+     similarly to the `B' macro otherwise.
+
+ -- Macro: .BX [txt]
+     Prints its argument and draws a box around it.  If you want to box
+     a string that contains spaces, use a digit-width space (`\0').
+
+ -- Macro: .UL [txt [post]]
+     Prints its first argument with an underline.  If you specify a
+     second argument, `groff' prints it in the previous font after the
+     underlined text, with no intervening space.
+
+ -- Macro: .LG
+     Prints all text following in larger type (two points larger than
+     the current point size) until the next font size, highlighting,
+     paragraph, or heading macro.  You can specify this macro multiple
+     times to enlarge the point size as needed.
+
+ -- Macro: .SM
+     Prints all text following in smaller type (two points smaller than
+     the current point size) until the next type size, highlighting,
+     paragraph, or heading macro.  You can specify this macro multiple
+     times to reduce the point size as needed.
+
+ -- Macro: .NL
+     Prints all text following in the normal point size (that is, the
+     value of the `PS' register).
+
+ -- String: \*[{]
+ -- String: \*[}]
+     Text enclosed with `\*{' and `\*}' is printed as a superscript.
+
+
+File: groff,  Node: Lists in ms,  Next: Indentation values in ms,  Prev: Highlighting in ms,  Up: ms Body Text
+
+4.3.5.4 Lists
+.............
+
+The `IP' macro handles duties for all lists.
+
+ -- Macro: .IP [marker [width]]
+     The MARKER is usually a bullet glyph (`\[bu]') for unordered
+     lists, a number (or auto-incrementing number register) for
+     numbered lists, or a word or phrase for indented (glossary-style)
+     lists.
+
+     The WIDTH specifies the indentation for the body of each list
+     item; its default unit is `n'.  Once specified, the indentation
+     remains the same for all list items in the document until specified
+     again.
+
+     The `PORPHANS' register (*note ms Document Control Registers::)
+     operates in conjunction with the `IP' macro, to inhibit the
+     printing of orphaned list markers at the bottom of any page.
+
+   The following is an example of a bulleted list.  
+
+
+     A bulleted list:
+     .IP \[bu] 2
+     lawyers
+     .IP \[bu]
+     guns
+     .IP \[bu]
+     money
+
+   Produces:
+
+
+     A bulleted list:
+
+     o lawyers
+
+     o guns
+
+     o money
+
+   The following is an example of a numbered list.  
+
+
+     .nr step 1 1
+     A numbered list:
+     .IP \n[step] 3
+     lawyers
+     .IP \n+[step]
+     guns
+     .IP \n+[step]
+     money
+
+   Produces:
+
+
+     A numbered list:
+
+     1. lawyers
+
+     2. guns
+
+     3. money
+
+   Note the use of the auto-incrementing number register in this
+example.
+
+   The following is an example of a glossary-style list.  
+
+
+     A glossary-style list:
+     .IP lawyers 0.4i
+     Two or more attorneys.
+     .IP guns
+     Firearms, preferably
+     large-caliber.
+     .IP money
+     Gotta pay for those
+     lawyers and guns!
+
+   Produces:
+
+
+     A glossary-style list:
+
+     lawyers
+           Two or more attorneys.
+
+     guns  Firearms, preferably large-caliber.
+
+     money
+           Gotta pay for those lawyers and guns!
+
+   In the last example, the `IP' macro places the definition on the
+same line as the term if it has enough space; otherwise, it breaks to
+the next line and starts the definition below the term.  This may or
+may not be the effect you want, especially if some of the definitions
+break and some do not.  The following examples show two possible ways
+to force a break.
+
+   The first workaround uses the `br' request to force a break after
+printing the term or label.
+
+
+     A glossary-style list:
+     .IP lawyers 0.4i
+     Two or more attorneys.
+     .IP guns
+     .br
+     Firearms, preferably large-caliber.
+     .IP money
+     Gotta pay for those lawyers and guns!
+
+   The second workaround uses the `\p' escape to force the break.  Note
+the space following the escape; this is important.  If you omit the
+space, `groff' prints the first word on the same line as the term or
+label (if it fits) *then* breaks the line.
+
+
+     A glossary-style list:
+     .IP lawyers 0.4i
+     Two or more attorneys.
+     .IP guns
+     \p Firearms, preferably large-caliber.
+     .IP money
+     Gotta pay for those lawyers and guns!
+
+   To set nested lists, use the `RS' and `RE' macros.  *Note
+Indentation values in ms::, for more information.  
+
+   For example:
+
+
+     .IP \[bu] 2
+     Lawyers:
+     .RS
+     .IP \[bu]
+     Dewey,
+     .IP \[bu]
+     Cheatham,
+     .IP \[bu]
+     and Howe.
+     .RE
+     .IP \[bu]
+     Guns
+
+   Produces:
+
+
+     o Lawyers:
+
+       o  Dewey,
+
+       o  Cheatham,
+
+       o  and Howe.
+
+     o Guns
+
+
+File: groff,  Node: Indentation values in ms,  Next: Tabstops in ms,  Prev: Lists in ms,  Up: ms Body Text
+
+4.3.5.5 Indentation values
+..........................
+
+In many situations, you may need to indentation a section of text while
+still wrapping and filling.  *Note Lists in ms::, for an example of
+nested lists.
+
+ -- Macro: .RS
+ -- Macro: .RE
+     These macros begin and end an indented section.  The `PI' register
+     controls the amount of indentation, allowing the indented text to
+     line up under hanging and indented paragraphs.
+
+   *Note ms Displays and Keeps::, for macros to indentation and turn off
+filling.
+
+
+File: groff,  Node: Tabstops in ms,  Next: ms Displays and Keeps,  Prev: Indentation values in ms,  Up: ms Body Text
+
+4.3.5.6 Tab Stops
+.................
+
+Use the `ta' request to define tab stops as needed.  *Note Tabs and
+Fields::.
+
+ -- Macro: .TA
+     Use this macro to reset the tab stops to the default for `ms'
+     (every 5n).  You can redefine the `TA' macro to create a different
+     set of default tab stops.
+
+
+File: groff,  Node: ms Displays and Keeps,  Next: ms Insertions,  Prev: Tabstops in ms,  Up: ms Body Text
+
+4.3.5.7 Displays and keeps
+..........................
+
+Use displays to show text-based examples or figures (such as code
+listings).
+
+   Displays turn off filling, so lines of code are displayed as-is
+without inserting `br' requests in between each line.  Displays can be
+"kept" on a single page, or allowed to break across pages.
+
+ -- Macro: .DS L
+ -- Macro: .LD
+ -- Macro: .DE
+     Left-justified display.  The `.DS L' call generates a page break,
+     if necessary, to keep the entire display on one page.  The `LD'
+     macro allows the display to break across pages.  The `DE' macro
+     ends the display.
+
+ -- Macro: .DS I
+ -- Macro: .ID
+ -- Macro: .DE
+     Indents the display as defined by the `DI' register.  The `.DS I'
+     call generates a page break, if necessary, to keep the entire
+     display on one page.  The `ID' macro allows the display to break
+     across pages.  The `DE' macro ends the display.
+
+ -- Macro: .DS B
+ -- Macro: .BD
+ -- Macro: .DE
+     Sets a block-centered display: the entire display is
+     left-justified, but indented so that the longest line in the
+     display is centered on the page.  The `.DS B' call generates a
+     page break, if necessary, to keep the entire display on one page.
+     The `BD' macro allows the display to break across pages.  The `DE'
+     macro ends the display.
+
+ -- Macro: .DS C
+ -- Macro: .CD
+ -- Macro: .DE
+     Sets a centered display: each line in the display is centered.  The
+     `.DS C' call generates a page break, if necessary, to keep the
+     entire display on one page.  The `CD' macro allows the display to
+     break across pages.  The `DE' macro ends the display.
+
+ -- Macro: .DS R
+ -- Macro: .RD
+ -- Macro: .DE
+     Right-justifies each line in the display.  The `.DS R' call
+     generates a page break, if necessary, to keep the entire display on
+     one page.  The `RD' macro allows the display to break across
+     pages.  The `DE' macro ends the display.
+
+ -- Macro: .Ds
+ -- Macro: .De
+     These two macros were formerly provided as aliases for `DS' and
+     `DE', respectively.  They have been removed, and should no longer
+     be used.  The original implementations of `DS' and `DE' are
+     retained, and should be used instead.  X11 documents which actually
+     use `Ds' and `De' always load a specific macro file from the X11
+     distribution (`macros.t') which provides proper definitions for
+     the two macros.
+
+   On occasion, you may want to "keep" other text together on a page.
+For example, you may want to keep two paragraphs together, or a
+paragraph that refers to a table (or list, or other item) immediately
+following.  The `ms' macros provide the `KS' and `KE' macros for this
+purpose.
+
+ -- Macro: .KS
+ -- Macro: .KE
+     The `KS' macro begins a block of text to be kept on a single page,
+     and the `KE' macro ends the block.
+
+ -- Macro: .KF
+ -- Macro: .KE
+     Specifies a "floating keep"; if the keep cannot fit on the current
+     page, `groff' holds the contents of the keep and allows text
+     following the keep (in the source file) to fill in the remainder of
+     the current page.  When the page breaks, whether by an explicit
+     `bp' request or by reaching the end of the page, `groff' prints
+     the floating keep at the top of the new page.  This is useful for
+     printing large graphics or tables that do not need to appear
+     exactly where specified.
+
+   You can also use the `ne' request to force a page break if there is
+not enough vertical space remaining on the page.
+
+   Use the following macros to draw a box around a section of text (such
+as a display).
+
+ -- Macro: .B1
+ -- Macro: .B2
+     Marks the beginning and ending of text that is to have a box drawn
+     around it.  The `B1' macro begins the box; the `B2' macro ends it.
+     Text in the box is automatically placed in a diversion (keep).
+
+
+File: groff,  Node: ms Insertions,  Next: Example multi-page table,  Prev: ms Displays and Keeps,  Up: ms Body Text
+
+4.3.5.8 Tables, figures, equations, and references
+..................................................
+
+The `ms' macros support the standard `groff' preprocessors: `tbl',
+`pic', `eqn', and `refer'.  You mark text meant for preprocessors by
+enclosing it in pairs of tags as follows.
+
+ -- Macro: .TS [`H']
+ -- Macro: .TE
+     Denotes a table, to be processed by the `tbl' preprocessor.  The
+     optional argument `H' to `TS' instructs `groff' to create a
+     running header with the information up to the `TH' macro.  `groff'
+     prints the header at the beginning of the table; if the table runs
+     onto another page, `groff' prints the header on the next page as
+     well.
+
+ -- Macro: .PS
+ -- Macro: .PE
+     Denotes a graphic, to be processed by the `pic' preprocessor.  You
+     can create a `pic' file by hand, using the AT&T `pic' manual
+     available on the Web as a reference, or by using a graphics
+     program such as `xfig'.
+
+ -- Macro: .EQ [align]
+ -- Macro: .EN
+     Denotes an equation, to be processed by the `eqn' preprocessor.
+     The optional ALIGN argument can be `C', `L', or `I' to center (the
+     default), left-justify, or indent the equation.
+
+ -- Macro: .[
+ -- Macro: .]
+     Denotes a reference, to be processed by the `refer' preprocessor.
+     The GNU `refer(1)' man page provides a comprehensive reference to
+     the preprocessor and the format of the bibliographic database.
+
+* Menu:
+
+* Example multi-page table::
+
+
+File: groff,  Node: Example multi-page table,  Next: ms Footnotes,  Prev: ms Insertions,  Up: ms Body Text
+
+4.3.5.9 An example multi-page table
+...................................
+
+The following is an example of how to set up a table that may print
+across two or more pages.
+
+
+     .TS H
+     allbox expand;
+     cb | cb .
+     Text      ...of heading...
+     _
+     .TH
+     .T&
+     l | l .
+     ... the rest of the table follows...
+     .CW
+     .TE
+
+
+File: groff,  Node: ms Footnotes,  Prev: Example multi-page table,  Up: ms Body Text
+
+4.3.5.10 Footnotes
+..................
+
+The `ms' macro package has a flexible footnote system.  You can specify
+either numbered footnotes or symbolic footnotes (that is, using a
+marker such as a dagger symbol).
+
+ -- String: \*[*]
+     Specifies the location of a numbered footnote marker in the text.
+
+ -- Macro: .FS
+ -- Macro: .FE
+     Specifies the text of the footnote.  The default action is to
+     create a numbered footnote; you can create a symbolic footnote by
+     specifying a "mark" glyph (such as `\[dg]' for the dagger glyph)
+     in the body text and as an argument to the `FS' macro, followed by
+     the text of the footnote and the `FE' macro.
+
+   You can control how `groff' prints footnote numbers by changing the
+value of the `FF' register.  *Note ms Document Control Registers::.
+
+   Footnotes can be safely used within keeps and displays, but you
+should avoid using numbered footnotes within floating keeps.  You can
+set a second `\**' marker between a `\**' and its corresponding `.FS'
+entry; as long as each `FS' macro occurs _after_ the corresponding
+`\**' and the occurrences of `.FS' are in the same order as the
+corresponding occurrences of `\**'.
+
+
+File: groff,  Node: ms Page Layout,  Next: Differences from AT&T ms,  Prev: ms Body Text,  Up: ms
+
+4.3.6 Page layout
+-----------------
+
+The default output from the `ms' macros provides a minimalist page
+layout: it prints a single column, with the page number centered at the
+top of each page.  It prints no footers.
+
+   You can change the layout by setting the proper number registers and
+strings.
+
+* Menu:
+
+* ms Headers and Footers::
+* ms Margins::
+* ms Multiple Columns::
+* ms TOC::
+* ms Strings and Special Characters::
+
+
+File: groff,  Node: ms Headers and Footers,  Next: ms Margins,  Prev: ms Page Layout,  Up: ms Page Layout
+
+4.3.6.1 Headers and footers
+...........................
+
+For documents that do not distinguish between odd and even pages, set
+the following strings:
+
+ -- String: \*[LH]
+ -- String: \*[CH]
+ -- String: \*[RH]
+     Sets the left, center, and right headers.
+
+ -- String: \*[LF]
+ -- String: \*[CF]
+ -- String: \*[RF]
+     Sets the left, center, and right footers.
+
+   For documents that need different information printed in the even and
+odd pages, use the following macros:
+
+ -- Macro: .OH 'left'center'right'
+ -- Macro: .EH 'left'center'right'
+ -- Macro: .OF 'left'center'right'
+ -- Macro: .EF 'left'center'right'
+     The `OH' and `EH' macros define headers for the odd and even
+     pages; the `OF' and `EF' macros define footers for the odd and
+     even pages.  This is more flexible than defining the individual
+     strings.
+
+     You can replace the quote (`'') marks with any character not
+     appearing in the header or footer text.
+
+
+File: groff,  Node: ms Margins,  Next: ms Multiple Columns,  Prev: ms Headers and Footers,  Up: ms Page Layout
+
+4.3.6.2 Margins
+...............
+
+You control margins using a set of number registers.  *Note ms Document
+Control Registers::, for details.
+
+
+File: groff,  Node: ms Multiple Columns,  Next: ms TOC,  Prev: ms Margins,  Up: ms Page Layout
+
+4.3.6.3 Multiple columns
+........................
+
+The `ms' macros can set text in as many columns as will reasonably fit
+on the page.  The following macros are available; all of them force a
+page break if a multi-column mode is already set.  However, if the
+current mode is single-column, starting a multi-column mode does _not_
+force a page break.
+
+ -- Macro: .1C
+     Single-column mode.
+
+ -- Macro: .2C
+     Two-column mode.
+
+ -- Macro: .MC [width [gutter]]
+     Multi-column mode.  If you specify no arguments, it is equivalent
+     to the `2C' macro.  Otherwise, WIDTH is the width of each column
+     and GUTTER is the space between columns.  The `MINGW' number
+     register controls the default gutter width.
+
+
+File: groff,  Node: ms TOC,  Next: ms Strings and Special Characters,  Prev: ms Multiple Columns,  Up: ms Page Layout
+
+4.3.6.4 Creating a table of contents
+....................................
+
+The facilities in the `ms' macro package for creating a table of
+contents are semi-automated at best.  Assuming that you want the table
+of contents to consist of the document's headings, you need to repeat
+those headings wrapped in `XS' and `XE' macros.
+
+ -- Macro: .XS [page]
+ -- Macro: .XA [page]
+ -- Macro: .XE
+     These macros define a table of contents or an individual entry in
+     the table of contents, depending on their use.  The macros are very
+     simple; they cannot indent a heading based on its level.  The
+     easiest way to work around this is to add tabs to the table of
+     contents string.  The following is an example:
+
+
+          .NH 1
+          Introduction
+          .XS
+          Introduction
+          .XE
+          .LP
+          ...
+          .CW
+          .NH 2
+          Methodology
+          .XS
+          Methodology
+          .XE
+          .LP
+          ...
+
+     You can manually create a table of contents by beginning with the
+     `XS' macro for the first entry, specifying the page number for
+     that entry as the argument to `XS'.  Add subsequent entries using
+     the `XA' macro, specifying the page number for that entry as the
+     argument to `XA'.  The following is an example:
+
+
+          .XS 1
+          Introduction
+          .XA 2
+          A Brief History of the Universe
+          .XA 729
+          Details of Galactic Formation
+          ...
+          .XE
+
+
+ -- Macro: .TC [`no']
+     Prints the table of contents on a new page, setting the page number
+     to *i* (Roman lowercase numeral one).  You should usually place
+     this macro at the end of the file, since `groff' is a single-pass
+     formatter and can only print what has been collected up to the
+     point that the `TC' macro appears.
+
+     The optional argument `no' suppresses printing the title specified
+     by the string register `TOC'.
+
+ -- Macro: .PX [`no']
+     Prints the table of contents on a new page, using the current page
+     numbering sequence.  Use this macro to print a manually-generated
+     table of contents at the beginning of your document.
+
+     The optional argument `no' suppresses printing the title specified
+     by the string register `TOC'.
+
+   The `Groff and Friends HOWTO' includes a `sed' script that
+automatically inserts `XS' and `XE' macro entries after each heading in
+a document.
+
+   Altering the `NH' macro to automatically build the table of contents
+is perhaps initially more difficult, but would save a great deal of
+time in the long run if you use `ms' regularly.
+
+
+File: groff,  Node: ms Strings and Special Characters,  Prev: ms TOC,  Up: ms Page Layout
+
+4.3.6.5 Strings and Special Characters
+......................................
+
+The `ms' macros provide the following predefined strings.  You can
+change the string definitions to help in creating documents in
+languages other than English.
+
+ -- String: \*[REFERENCES]
+     Contains the string printed at the beginning of the references
+     (bibliography) page.  The default is `References'.
+
+ -- String: \*[ABSTRACT]
+     Contains the string printed at the beginning of the abstract.  The
+     default is `ABSTRACT'.
+
+ -- String: \*[TOC]
+     Contains the string printed at the beginning of the table of
+     contents.
+
+ -- String: \*[MONTH1]
+ -- String: \*[MONTH2]
+ -- String: \*[MONTH3]
+ -- String: \*[MONTH4]
+ -- String: \*[MONTH5]
+ -- String: \*[MONTH6]
+ -- String: \*[MONTH7]
+ -- String: \*[MONTH8]
+ -- String: \*[MONTH9]
+ -- String: \*[MONTH10]
+ -- String: \*[MONTH11]
+ -- String: \*[MONTH12]
+     Prints the full name of the month in dates.  The default is
+     `January', `February', etc.
+
+   The following special characters are available(1) (*note ms Strings
+and Special Characters-Footnote-1::):
+
+ -- String: \*[-]
+     Prints an em dash.
+
+ -- String: \*[Q]
+ -- String: \*[U]
+     Prints typographer's quotes in troff, and plain quotes in nroff.
+     `\*Q' is the left quote and `\*U' is the right quote.
+
+   Improved accent marks are available in the `ms' macros.
+
+ -- Macro: .AM
+     Specify this macro at the beginning of your document to enable
+     extended accent marks and special characters.  This is a Berkeley
+     extension.
+
+     To use the accent marks, place them *after* the character being
+     accented.
+
+     Note that groff's native support for accents is superior to the
+     following definitions.
+
+   The following accent marks are available after invoking the `AM'
+macro:
+
+ -- String: \*[']
+     Acute accent.
+
+ -- String: \*[`]
+     Grave accent.
+
+ -- String: \*[^]
+     Circumflex.
+
+ -- String: \*[,]
+     Cedilla.
+
+ -- String: \*[~]
+     Tilde.
+
+ -- String: \*[:]
+     Umlaut.
+
+ -- String: \*[v]
+     Hacek.
+
+ -- String: \*[_]
+     Macron (overbar).
+
+ -- String: \*[.]
+     Underdot.
+
+ -- String: \*[o]
+     Ring above.
+
+   The following are standalone characters available after invoking the
+`AM' macro:
+
+ -- String: \*[?]
+     Upside-down question mark.
+
+ -- String: \*[!]
+     Upside-down exclamation point.
+
+ -- String: \*[8]
+     German ß ligature.
+
+ -- String: \*[3]
+     Yogh.
+
+ -- String: \*[Th]
+     Uppercase thorn.
+
+ -- String: \*[th]
+     Lowercase thorn.
+
+ -- String: \*[D-]
+     Uppercase eth.
+
+ -- String: \*[d-]
+     Lowercase eth.
+
+ -- String: \*[q]
+     Hooked o.
+
+ -- String: \*[ae]
+     Lowercase æ ligature.
+
+ -- String: \*[Ae]
+     Uppercase Æ ligature.
+
+
+File: groff,  Node: ms Strings and Special Characters-Footnotes,  Up: ms Strings and Special Characters
+
+   (1) For an explanation what special characters are see *Note Special
+Characters::.
+
+
+File: groff,  Node: Differences from AT&T ms,  Next: Naming Conventions,  Prev: ms Page Layout,  Up: ms
+
+4.3.7 Differences from AT&T `ms'
+--------------------------------
+
+This section lists the (minor) differences between the `groff -ms'
+macros and AT&T `troff -ms' macros.
+
+   * The internals of `groff -ms' differ from the internals of AT&T
+     `troff -ms'.  Documents that depend upon implementation details of
+     AT&T `troff -ms' may not format properly with `groff -ms'.
+
+   * The general error-handling policy of `groff -ms' is to detect and
+     report errors, rather than silently to ignore them.
+
+   * `groff -ms' does not work in compatibility mode (this is, with the
+     `-C' option).
+
+   * There is no special support for typewriter-like devices.
+
+   * `groff -ms' does not provide cut marks.
+
+   * Multiple line spacing is not supported.  Use a larger vertical
+     spacing instead.
+
+   * Some UNIX `ms' documentation says that the `CW' and `GW' number
+     registers can be used to control the column width and gutter
+     width, respectively.  These number registers are not used in
+     `groff -ms'.
+
+   * Macros that cause a reset (paragraphs, headings, etc.) may change
+     the indentation.  Macros that change the indentation do not
+     increment or decrement the indentation, but rather set it
+     absolutely.  This can cause problems for documents that define
+     additional macros of their own.  The solution is to use not the
+     `in' request but instead the `RS' and `RE' macros.
+
+   * To make `groff -ms' use the default page offset (which also
+     specifies the left margin), the `PO' register must stay undefined
+     until the first `-ms' macro is evaluated.  This implies that `PO'
+     should not be used early in the document, unless it is changed
+     also: Remember that accessing an undefined register automatically
+     defines it.
+
+ -- Register: \n[GS]
+     This number register is set to 1 by the `groff -ms' macros, but it
+     is not used by the `AT&T' `troff -ms' macros.  Documents that need
+     to determine whether they are being formatted with `AT&T' `troff
+     -ms' or `groff -ms' should use this number register.
+
+* Menu:
+
+* Missing ms Macros::
+* Additional ms Macros::
+
+
+File: groff,  Node: Missing ms Macros,  Next: Additional ms Macros,  Prev: Differences from AT&T ms,  Up: Differences from AT&T ms
+
+4.3.7.1 `troff' macros not appearing in `groff'
+...............................................
+
+Macros missing from `groff -ms' are cover page macros specific to Bell
+Labs and Berkeley.  The macros known to be missing are:
+
+`.TM'
+     Technical memorandum; a cover sheet style
+
+`.IM'
+     Internal memorandum; a cover sheet style
+
+`.MR'
+     Memo for record; a cover sheet style
+
+`.MF'
+     Memo for file; a cover sheet style
+
+`.EG'
+     Engineer's notes; a cover sheet style
+
+`.TR'
+     Computing Science Tech Report; a cover sheet style
+
+`.OK'
+     Other keywords
+
+`.CS'
+     Cover sheet information
+
+`.MH'
+     A cover sheet macro
+
+
+File: groff,  Node: Additional ms Macros,  Prev: Missing ms Macros,  Up: Differences from AT&T ms
+
+4.3.7.2 `groff' macros not appearing in AT&T `troff'
+....................................................
+
+The `groff -ms' macros have a few minor extensions compared to the AT&T
+`troff -ms' macros.
+
+ -- Macro: .AM
+     Improved accent marks.  *Note ms Strings and Special Characters::,
+     for details.
+
+ -- Macro: .DS I
+     Indented display.  The default behavior of AT&T `troff -ms' was to
+     indent; the `groff' default prints displays flush left with the
+     body text.
+
+ -- Macro: .CW
+     Print text in `constant width' (Courier) font.
+
+ -- Macro: .IX
+     Indexing term (printed on standard error).  You can write a script
+     to capture and process an index generated in this manner.
+
+   The following additional number registers appear in `groff -ms':
+
+ -- Register: \n[MINGW]
+     Specifies a minimum space between columns (for multi-column
+     output); this takes the place of the `GW' register that was
+     documented but apparently not implemented in AT&T `troff'.
+
+   Several new string registers are available as well.  You can change
+these to handle (for example) the local language.  *Note ms Strings and
+Special Characters::, for details.
+
+
+File: groff,  Node: Naming Conventions,  Prev: Differences from AT&T ms,  Up: ms
+
+4.3.8 Naming Conventions
+------------------------
+
+The following conventions are used for names of macros, strings and
+number registers.  External names available to documents that use the
+`groff -ms' macros contain only uppercase letters and digits.
+
+   Internally the macros are divided into modules; naming conventions
+are as follows:
+
+   * Names used only within one module are of the form MODULE`*'NAME.
+
+   * Names used outside the module in which they are defined are of the
+     form MODULE`@'NAME.
+
+   * Names associated with a particular environment are of the form
+     ENVIRONMENT`:'NAME; these are used only within the `par' module.
+
+   * NAME does not have a module prefix.
+
+   * Constructed names used to implement arrays are of the form
+     ARRAY`!'INDEX.
+
+   Thus the groff ms macros reserve the following names:
+
+   * Names containing the characters `*', `@', and `:'.
+
+   * Names containing only uppercase letters and digits.
+
+
+File: groff,  Node: me,  Next: mm,  Prev: ms,  Up: Macro Packages
+
+4.4 `me'
+========
+
+See the `meintro.me' and `meref.me' documents in groff's `doc'
+directory.
+
+
+File: groff,  Node: mm,  Prev: me,  Up: Macro Packages
+
+4.5 `mm'
+========
+
+See the `groff_mm(7)' man page (type `man groff_mm' at the command
+line).
+
+
+File: groff,  Node: gtroff Reference,  Next: Preprocessors,  Prev: Macro Packages,  Up: Top
+
+5 `gtroff' Reference
+********************
+
+This chapter covers *all* of the facilities of `gtroff'.  Users of
+macro packages may skip it if not interested in details.
+
+* Menu:
+
+* Text::
+* Measurements::
+* Expressions::
+* Identifiers::
+* Embedded Commands::
+* Registers::
+* Manipulating Filling and Adjusting::
+* Manipulating Hyphenation::
+* Manipulating Spacing::
+* Tabs and Fields::
+* Character Translations::
+* Troff and Nroff Mode::
+* Line Layout::
+* Line Control::
+* Page Layout::
+* Page Control::
+* Fonts and Symbols::
+* Sizes::
+* Strings::
+* Conditionals and Loops::
+* Writing Macros::
+* Page Motions::
+* Drawing Requests::
+* Traps::
+* Diversions::
+* Environments::
+* Suppressing output::
+* Colors::
+* I/O::
+* Postprocessor Access::
+* Miscellaneous::
+* Gtroff Internals::
+* Debugging::
+* Implementation Differences::
+
+
+File: groff,  Node: Text,  Next: Measurements,  Prev: gtroff Reference,  Up: gtroff Reference
+
+5.1 Text
+========
+
+`gtroff' input files contain text with control commands interspersed
+throughout.  But, even without control codes, `gtroff' still does
+several things with the input text:
+
+   * filling and adjusting
+
+   * adding additional space after sentences
+
+   * hyphenating
+
+   * inserting implicit line breaks
+
+* Menu:
+
+* Filling and Adjusting::
+* Hyphenation::
+* Sentences::
+* Tab Stops::
+* Implicit Line Breaks::
+* Input Conventions::
+* Input Encodings::
+
+
+File: groff,  Node: Filling and Adjusting,  Next: Hyphenation,  Prev: Text,  Up: Text
+
+5.1.1 Filling and Adjusting
+---------------------------
+
+When `gtroff' reads text, it collects words from the input and fits as
+many of them together on one output line as it can.  This is known as
+"filling".
+
+   Once `gtroff' has a "filled" line, it tries to "adjust" it.  This
+means it widens the spacing between words until the text reaches the
+right margin (in the default adjustment mode).  Extra spaces between
+words are preserved, but spaces at the end of lines are ignored.
+Spaces at the front of a line cause a "break" (breaks are explained in
+*Note Implicit Line Breaks::).
+
+   *Note Manipulating Filling and Adjusting::.
+
+
+File: groff,  Node: Hyphenation,  Next: Sentences,  Prev: Filling and Adjusting,  Up: Text
+
+5.1.2 Hyphenation
+-----------------
+
+Since the odds are not great for finding a set of words, for every
+output line, which fit nicely on a line without inserting excessive
+amounts of space between words, `gtroff' hyphenates words so that it
+can justify lines without inserting too much space between words.  It
+uses an internal hyphenation algorithm (a simplified version of the
+algorithm used within TeX) to indicate which words can be hyphenated
+and how to do so.  When a word is hyphenated, the first part of the
+word is added to the current filled line being output (with an attached
+hyphen), and the other portion is added to the next line to be filled.
+
+   *Note Manipulating Hyphenation::.
+
+
+File: groff,  Node: Sentences,  Next: Tab Stops,  Prev: Hyphenation,  Up: Text
+
+5.1.3 Sentences
+---------------
+
+Although it is often debated, some typesetting rules say there should be
+different amounts of space after various punctuation marks.  For
+example, the `Chicago typsetting manual' says that a period at the end
+of a sentence should have twice as much space following it as would a
+comma or a period as part of an abbreviation.
+
+   `gtroff' does this by flagging certain characters (normally `!',
+`?', and `.') as "end-of-sentence" characters.  When `gtroff'
+encounters one of these characters at the end of a line, it appends a
+normal space followed by a "sentence space" in the formatted output.
+(This justifies one of the conventions mentioned in *Note Input
+Conventions::.)
+
+   In addition, the following characters and symbols are treated
+transparently while handling end-of-sentence characters: `"', `'', `)',
+`]', `*', `\[dg]', and `\[rq]'.
+
+   See the `cflags' request in *Note Using Symbols::, for more details.
+
+   To prevent the insertion of extra space after an end-of-sentence
+character (at the end of a line), append `\&'.
+
+
+File: groff,  Node: Tab Stops,  Next: Implicit Line Breaks,  Prev: Sentences,  Up: Text
+
+5.1.4 Tab Stops
+---------------
+
+`gtroff' translates "tabulator characters", also called "tabs"
+(normally code point ASCII `0x09' or EBCDIC `0x05'), in the input into
+movements to the next tabulator stop.  These tab stops are initially
+located every half inch across the page.  Using this, simple tables can
+be made easily.  However, it can often be deceptive as the appearance
+(and width) of the text on a terminal and the results from `gtroff' can
+vary greatly.
+
+   Also, a possible sticking point is that lines beginning with tab
+characters are still filled, again producing unexpected results.  For
+example, the following input
+
+           1          2          3
+                      4          5
+
+produces
+
+           1          2          3                     4          5
+
+   *Note Tabs and Fields::.
+
+
+File: groff,  Node: Implicit Line Breaks,  Next: Input Conventions,  Prev: Tab Stops,  Up: Text
+
+5.1.5 Implicit Line Breaks
+--------------------------
+
+An important concept in `gtroff' is the "break".  When a break occurs,
+`gtroff' outputs the partially filled line (unjustified), and resumes
+collecting and filling text on the next output line.
+
+   There are several ways to cause a break in `gtroff'.  A blank line
+not only causes a break, but it also outputs a one-line vertical space
+(effectively a blank line).  Note that this behaviour can be modified
+with the blank line macro request `blm'.  *Note Blank Line Traps::.
+
+   A line that begins with a space causes a break and the space is
+output at the beginning of the next line.  Note that this space isn't
+adjusted, even in fill mode.
+
+   The end of file also causes a break - otherwise the last line of the
+document may vanish!
+
+   Certain requests also cause breaks, implicitly or explicitly.  This
+is discussed in *Note Manipulating Filling and Adjusting::.
+
+
+File: groff,  Node: Input Conventions,  Next: Input Encodings,  Prev: Implicit Line Breaks,  Up: Text
+
+5.1.6 Input Conventions
+-----------------------
+
+Since `gtroff' does filling automatically, it is traditional in `groff'
+not to try and type things in as nicely formatted paragraphs.  These
+are some conventions commonly used when typing `gtroff' text:
+
+   * Break lines after punctuation, particularly at the end of a
+     sentence and in other logical places.  Keep separate phrases on
+     lines by themselves, as entire phrases are often added or deleted
+     when editing.
+
+   * Try to keep lines less than 40-60 characters, to allow space for
+     inserting more text.
+
+   * Do not try to do any formatting in a WYSIWYG manner (i.e., don't
+     try using spaces to get proper indentation).
+
+
+File: groff,  Node: Input Encodings,  Prev: Input Conventions,  Up: Text
+
+5.1.7 Input Encodings
+---------------------
+
+Currently, the following input encodings are available.
+
+cp1047
+     This input encoding works only on EBCDIC platforms (and vice
+     versa, the other input encodings don't work with EBCDIC); the file
+     `cp1047.tmac' is by default loaded at start-up.
+
+latin-1
+     This is the default input encoding on non-EBCDIC platforms; the
+     file `latin1.tmac' is loaded at start-up.
+
+latin-2
+     To use this encoding, either say `.mso latin2.tmac' at the very
+     beginning of your document or use `-mlatin2' as a command line
+     argument for `groff'.
+
+latin-9 (latin-0)
+     This encoding is intended (at least in Europe) to replace latin-1
+     encoding.  The main difference to latin-1 is that latin-9 contains
+     the Euro character.  To use this encoding, either say
+     `.mso latin9.tmac' at the very beginning of your document or use
+     `-mlatin9' as a command line argument for `groff'.
+
+   Note that it can happen that some input encoding characters are not
+available for a particular output device.  For example, saying
+
+
+     groff -Tlatin1 -mlatin9 ...
+
+will fail if you use the Euro character in the input.  Usually, this
+limitation is present only for devices which have a limited set of
+output glyphs (e.g. `-Tascii' and `-Tlatin1'); for other devices it is
+usually sufficient to install proper fonts which contain the necessary
+glyphs.
+
+   Due to the importance of the Euro glyph in Europe, the groff package
+now comes with a POSTSCRIPT font called `freeeuro.pfa' which provides
+various glyph shapes for the Euro.  With other words, latin-9 encoding
+is supported for the `-Tps' device out of the box (latin-2 isn't).
+
+   By its very nature, `-Tutf8' supports all input encodings; `-Tdvi'
+has support for both latin-2 and latin-9 if the command line `-mec' is
+used also to load the file `ec.tmac' (which flips to the EC fonts).
+
+
+File: groff,  Node: Measurements,  Next: Expressions,  Prev: Text,  Up: gtroff Reference
+
+5.2 Measurements
+================
+
+`gtroff' (like many other programs) requires numeric parameters to
+specify various measurements.  Most numeric parameters(1) (*note
+Measurements-Footnote-1::) may have a "measurement unit" attached.
+These units are specified as a single character which immediately
+follows the number or expression.  Each of these units are understood,
+by `gtroff', to be a multiple of its "basic unit".  So, whenever a
+different measurement unit is specified `gtroff' converts this into its
+"basic units".  This basic unit, represented by a `u', is a device
+dependent measurement which is quite small, ranging from 1/75th to
+1/72000th of an inch.  The values may be given as fractional numbers;
+however, fractional basic units are always rounded to integers.
+
+   Some of the measurement units are completely independent of any of
+the current settings (e.g. type size) of `gtroff'.
+
+`i'
+     Inches.  An antiquated measurement unit still in use in certain
+     backwards countries with incredibly low-cost computer equipment.
+     One inch is equal to 2.54cm.
+
+`c'
+     Centimeters.  One centimeter is equal to 0.3937in.
+
+`p'
+     Points.  This is a typesetter's measurement used for measure type
+     size.  It is 72 points to an inch.
+
+`P'
+     Pica.  Another typesetting measurement.  6 Picas to an inch (and
+     12 points to a pica).
+
+`s'
+`z'
+     *Note Fractional Type Sizes::, for a discussion of these units.
+
+`f'
+     Fractions. Value is 65536.  *Note Colors::, for usage.
+
+   The other measurements understood by `gtroff' depend on settings
+currently in effect in `gtroff'.  These are very useful for specifying
+measurements which should look proper with any size of text.
+
+`m'
+     Ems.  This unit is equal to the current font size in points.  So
+     called because it is _approximately_ the width of the letter `m'
+     in the current font.
+
+`n'
+     Ens.  In `groff', this is half of an em.
+
+`v'
+     Vertical space.  This is equivalent to the current line spacing.
+     *Note Sizes::, for more information about this.
+
+`M'
+     100ths of an em.
+
+* Menu:
+
+* Default Units::
+
+
+File: groff,  Node: Measurements-Footnotes,  Up: Measurements
+
+   (1) those that specify vertical or horizontal motion or a type size
+
+
+File: groff,  Node: Default Units,  Prev: Measurements,  Up: Measurements
+
+5.2.1 Default Units
+-------------------
+
+Many requests take a default unit.  While this can be helpful at times,
+it can cause strange errors in some expressions.  For example, the line
+length request expects em units.  Here are several attempts to get a
+line length of 3.5 inches and their results:
+
+
+     3.5i      =>   3.5i
+     7/2       =>   0i
+     7/2i      =>   0i
+     (7 / 2)u  =>   0i
+     7i/2      =>   0.1i
+     7i/2u     =>   3.5i
+
+Everything is converted to basic units first.  In the above example it
+is assumed that 1i equals 240u, and 1m equals 10p (thus 1m equals 33u).
+The value 7i/2 is first handled as 7i/2m, then converted to 1680u/66u
+which is 25u, and this is approximately 0.1i.  As can be seen, a
+scaling indicator after a closing parenthesis is simply ignored.
+
+   Thus, the safest way to specify measurements is to always attach a
+scaling indicator.  If you want to multiply or divide by a certain
+scalar value, use `u' as the unit for that value.
+
+
+File: groff,  Node: Expressions,  Next: Identifiers,  Prev: Measurements,  Up: gtroff Reference
+
+5.3 Expressions
+===============
+
+`gtroff' has most arithmetic operators common to other languages:
+
+   * Arithmetic: `+' (addition), `-' (subtraction), `/' (division), `*'
+     (multiplication), `%' (modulo).
+
+     `gtroff' only provides integer arithmetic.  The internal type used
+     for computing results is `int', which is usually a 32bit signed
+     integer.
+
+   * Comparison: `<' (less than), `>' (greater than), `<=' (less than
+     or equal), `>=' (greater than or equal), `=' (equal), `==' (the
+     same as `=').
+
+   * Logical: `&' (logical and), `:' (logical or).
+
+   * Unary operators: `-' (negating, i.e. changing the sign), `+' (just
+     for completeness; does nothing in expressions), `!' (logical not;
+     this works only within `if' and `while' requests).  See below for
+     the use of unary operators in motion requests.
+
+   * Extrema: `>?' (maximum), `<?' (minimum).
+
+     Example:
+
+
+          .nr x 5
+          .nr y 3
+          .nr z (\n[x] >? \n[y])
+
+     The register `z' now contains 5.
+
+   * Scaling: `(C;E)'.  Evaluate E using C as the default scaling
+     indicator.  If C is missing, ignore scaling indicators in the
+     evaluation of E.
+
+   Parentheses may be used as in any other language.  However, in
+`gtroff' they are necessary to ensure order of evaluation.  `gtroff'
+has no operator precedence; expressions are evaluated left to right.
+This means that `gtroff' evaluates `3+5*4' as if it were parenthesized
+like `(3+5)*4', not as `3+(5*4)', as might be expected.
+
+   For many requests which cause a motion on the page, the unary
+operators `+' and `-' work differently if leading an expression.  They
+then indicate a motion relative to the current position (down or up,
+respectively).
+
+   Similarly, a leading `|' operator indicates an absolute position.
+For vertical movements, it specifies the distance from the top of the
+page; for horizontal movements, it gives the distance from the beginning
+of the _input_ line.
+
+   `+' and `-' are also treated differently by the following requests
+and escapes: `bp', `in', `ll', `lt', `nm', `nr', `pl', `pn', `po', `ps',
+`pvs', `rt', `ti', `\H', `\R', and `\s'.  Here, leading plus and minus
+signs indicate increments and decrements.
+
+   *Note Setting Registers::, for some examples.
+
+ -- Escape: \B'anything'
+     Return 1 if ANYTHING is a valid numeric expression; or 0 if
+     ANYTHING is empty or not a valid numeric expression.
+
+   Due to the way arguments are parsed, spaces are not allowed in
+expressions, unless the entire expression is surrounded by parentheses.
+
+   *Note Request and Macro Arguments::, and *Note Conditionals and
+Loops::.
+
+
+File: groff,  Node: Identifiers,  Next: Embedded Commands,  Prev: Expressions,  Up: gtroff Reference
+
+5.4 Identifiers
+===============
+
+Like any other language, `gtroff' has rules for properly formed
+"identifiers".  In `gtroff', an identifier can be made up of almost any
+printable character, with the exception of the following characters:
+
+   * Whitespace characters (spaces, tabs, and newlines).
+
+   * Backspace (ASCII `0x08' or EBCDIC `0x16') and character code
+     `0x01'.
+
+   * The following input characters are invalid and are ignored if
+     `groff' runs on a machine based on ASCII, causing a warning
+     message of type `input' (see *Note Debugging::, for more details):
+     `0x00', `0x0B', `0x0D'-`0x1F', `0x80'-`0x9F'.
+
+     And here are the invalid input characters if `groff' runs on an
+     EBCDIC host: `0x00', `0x08', `0x09', `0x0B', `0x0D'-`0x14',
+     `0x17'-`0x1F', `0x30'-`0x3F'.
+
+     Currently, some of these reserved codepoints are used internally,
+     thus making it non-trivial to extend `gtroff' to cover Unicode or
+     other character sets and encodings which use characters of these
+     ranges.
+
+     Note that invalid characters are removed before parsing; an
+     identifier `foo', followed by an invalid character, followed by
+     `bar' is treated as `foobar'.
+
+   For example, any of the following is valid.
+
+
+     br
+     PP
+     (l
+     end-list
+     @_
+
+Note that identifiers longer than two characters with a closing bracket
+(`]') in its name can't be accessed with escape sequences which expect
+an identifier as a parameter.  For example, `\[foo]]' accesses the
+glyph `foo', followed by `]', whereas `\C'foo]'' really asks for glyph
+`foo]'.
+
+   To avoid problems with the `refer' preprocessor, macro names should
+not start with `[' or `]'.  Due to backwards compatibility, everything
+after `.[' and `.]' is handled as a special argument to `refer'.  For
+example, `.[foo' makes `refer' to start a reference, using `foo' as a
+parameter.
+
+ -- Escape: \A'ident'
+     Test whether an identifier IDENT is valid in `gtroff'.  It expands
+     to the character 1 or 0 according to whether its argument (usually
+     delimited by quotes) is or is not acceptable as the name of a
+     string, macro, diversion, number register, environment, or font.
+     It returns 0 if no argument is given.  This is useful for looking
+     up user input in some sort of associative table.
+
+
+          \A'end-list'
+              => 1
+
+
+   *Note Escapes::, for details on parameter delimiting characters.
+
+   Identifiers in `gtroff' can be any length, but, in some contexts,
+`gtroff' needs to be told where identifiers end and text begins (and in
+different ways depending on their length):
+
+   * Single character.
+
+   * Two characters.  Must be prefixed with `(' in some situations.
+
+   * Arbitrary length (`gtroff' only).  Must be bracketed with `['
+     and `]' in some situations.  Any length identifier can be put in
+     brackets.
+
+   Unlike many other programming languages, undefined identifiers are
+silently ignored or expanded to nothing.  When `gtroff' finds an
+undefined identifier, it emits a warning, doing the following:
+
+   * If the identifier is a string, macro, or diversion, `gtroff'
+     defines it as empty.
+
+   * If the identifier is a number register, `gtroff' defines it with a
+     value of 0.
+
+   *Note Warnings::., *Note Interpolating Registers::, and *Note
+Strings::.
+
+   Note that macros, strings, and diversions share the same name space.
+
+
+     .de xxx
+     .  nop foo
+     ..
+     .
+     .di xxx
+     bar
+     .br
+     .di
+     .
+     .xxx
+         => bar
+
+As can be seen in the previous example, `gtroff' reuses the identifier
+`xxx', changing it from a macro to a diversion.  No warning is emitted!
+The contents of the first macro definition is lost.
+
+   *Note Interpolating Registers::, and *Note Strings::.
+
+
+File: groff,  Node: Embedded Commands,  Next: Registers,  Prev: Identifiers,  Up: gtroff Reference
+
+5.5 Embedded Commands
+=====================
+
+Most documents need more functionality beyond filling, adjusting and
+implicit line breaking.  In order to gain further functionality,
+`gtroff' allows commands to be embedded into the text, in two ways.
+
+   The first is a "request" which takes up an entire line, and does
+some large-scale operation (e.g. break lines, start new pages).
+
+   The other is an "escape" which can be usually embedded anywhere in
+the text; most requests can accept it even as an argument.  Escapes
+generally do more minor operations like sub- and superscripts, print a
+symbol, etc.
+
+* Menu:
+
+* Requests::
+* Macros::
+* Escapes::
+
+
+File: groff,  Node: Requests,  Next: Macros,  Prev: Embedded Commands,  Up: Embedded Commands
+
+5.5.1 Requests
+--------------
+
+A request line begins with a control character, which is either a single
+quote (`'', the "no-break control character") or a period (`.', the
+normal "control character").  These can be changed; see *Note Character
+Translations::, for details.  After this there may be optional tabs or
+spaces followed by an identifier which is the name of the request.
+This may be followed by any number of space-separated arguments (_no_
+tabs here).
+
+   Since a control character followed by whitespace only is ignored, it
+is common practice to use this feature for structuring the source code
+of documents or macro packages.
+
+
+     .de foo
+     .  tm This is foo.
+     ..
+     .
+     .
+     .de bar
+     .  tm This is bar.
+     ..
+
+   Another possibility is to use the blank line macro request `blm' by
+assigning an empty macro to it.
+
+
+     .de do-nothing
+     ..
+     .blm do-nothing  \" activate blank line macro
+
+     .de foo
+     .  tm This is foo.
+     ..
+
+
+     .de bar
+     .  tm This is bar.
+     ..
+
+     .blm             \" deactivate blank line macro
+
+   *Note Blank Line Traps::.
+
+   To begin a line with a control character without it being
+interpreted, precede it with `\&'.  This represents a zero width space,
+which means it does not affect the output.
+
+   In most cases the period is used as a control character.  Several
+requests cause a break implicitly; using the single quote control
+character prevents this.
+
+* Menu:
+
+* Request and Macro Arguments::
+
+
+File: groff,  Node: Request and Macro Arguments,  Prev: Requests,  Up: Requests
+
+5.5.1.1 Request and Macro Arguments
+...................................
+
+Arguments to requests and macros are processed much like the shell: The
+line is split into arguments according to spaces.(1) (*note Request and
+Macro Arguments-Footnote-1::)
+
+   An argument to a macro which is intended to contain spaces can
+either be enclosed in double quotes, or have the spaces "escaped" with
+backslashes.  This is _not_ true for requests.
+
+   Here are a few examples for a hypothetical macro `uh':
+
+
+     .uh The Mouse Problem
+     .uh "The Mouse Problem"
+     .uh The\ Mouse\ Problem
+
+The first line is the `uh' macro being called with 3 arguments, `The',
+`Mouse', and `Problem'.  The latter two have the same effect of calling
+the `uh' macro with one argument, `The Mouse Problem'.(2) (*note
+Request and Macro Arguments-Footnote-2::)
+
+   A double quote which isn't preceded by a space doesn't start a macro
+argument.  If not closing a string, it is printed literally.
+
+   For example,
+
+
+     .xxx a" "b c" "de"fg"
+
+has the arguments `a"', `b c', `de', and `fg"'.  Don't rely on this
+obscure behaviour!
+
+   There are two possibilities to get a double quote reliably.
+
+   * Enclose the whole argument with double quotes and use two
+     consecutive double quotes to represent a single one.  This
+     traditional solution has the disadvantage that double quotes don't
+     survive argument expansion again if called in compatibility mode
+     (using the `-C' option of `groff'):
+
+
+          .de xx
+          .  tm xx: `\\$1' `\\$2' `\\$3'
+          .
+          .  yy "\\$1" "\\$2" "\\$3"
+          ..
+          .de yy
+          .  tm yy: `\\$1' `\\$2' `\\$3'
+          ..
+          .xx A "test with ""quotes""" .
+              => xx: `A' `test with "quotes"' `.'
+              => yy: `A' `test with ' `quotes""'
+
+     If not in compatibility mode, you get the expected result
+
+
+          xx: `A' `test with "quotes"' `.'
+          yy: `A' `test with "quotes"' `.'
+
+     since `gtroff' preserves the input level.
+
+   * Use the double quote glyph `\(dq'.  This works with and without
+     compatibility mode enabled since `gtroff' doesn't convert `\(dq'
+     back to a double quote input character.
+
+     Not that this method won't work with UNIX `troff' in general since
+     the glyph `dq' isn't defined normally.
+
+   Double quotes in the `ds' request are handled differently.  *Note
+Strings::, for more details.
+
+
+File: groff,  Node: Request and Macro Arguments-Footnotes,  Up: Request and Macro Arguments
+
+   (1) Plan 9's `troff' implementation also allows tabs for argument
+separation - `gtroff' intentionally doesn't support this.
+
+   (2) The last solution, i.e., using escaped spaces, is "classical" in
+the sense that it can be found in most `troff' documents.
+Nevertheless, it is not optimal in all situations, since `\ ' inserts a
+fixed-width, non-breaking space character which can't stretch.
+`gtroff' provides a different command `\~' to insert a stretchable,
+non-breaking space.
+
+
+File: groff,  Node: Macros,  Next: Escapes,  Prev: Requests,  Up: Embedded Commands
+
+5.5.2 Macros
+------------
+
+`gtroff' has a "macro" facility for defining a series of lines which
+can be invoked by name.  They are called in the same manner as requests
+- arguments also may be passed basically in the same manner.
+
+   *Note Writing Macros::, and *Note Request and Macro Arguments::.
+
+
+File: groff,  Node: Escapes,  Prev: Macros,  Up: Embedded Commands
+
+5.5.3 Escapes
+-------------
+
+Escapes may occur anywhere in the input to `gtroff'.  They usually
+begin with a backslash and are followed by a single character which
+indicates the function to be performed.  The escape character can be
+changed; see *Note Character Translations::.
+
+   Escape sequences which require an identifier as a parameter accept
+three possible syntax forms.
+
+   * The next single character is the identifier.
+
+   * If this single character is an opening parenthesis, take the
+     following two characters as the identifier.  Note that there is no
+     closing parenthesis after the identifier.
+
+   * If this single character is an opening bracket, take all characters
+     until a closing bracket as the identifier.
+
+Examples:
+
+
+     \fB
+     \n(XX
+     \*[TeX]
+
+   Other escapes may require several arguments and/or some special
+format.  In such cases the argument is traditionally enclosed in single
+quotes (and quotes are always used in this manual for the definitions
+of escape sequences).  The enclosed text is then processed according to
+what that escape expects.  Example:
+
+
+     \l'1.5i\(bu'
+
+   Note that the quote character can be replaced with any other
+character which does not occur in the argument (even a newline or a
+space character) in the following escapes: `\o', `\b', and `\X'.  This
+makes e.g.
+
+
+     A caf
+     \o
+     e\'
+
+
+     in Paris
+       => A café in Paris
+
+possible, but it is better not to use this feature to avoid confusion.
+
+   The following escapes sequences (which are handled similarly to
+characters since they don't take a parameter) are also allowed as
+delimiters: `\%', `\ ', `\|', `\^', `\{', `\}', `\'', `\`', `\-', `\_',
+`\!', `\?', `\@', `\)', `\/', `\,', `\&', `\:', `\~', `\0', `\a', `\c',
+`\d', `\e', `\E', `\p', `\r', `\t', and `\u'.  Again, don't use these
+if possible.
+
+   No newline characters as delimiters are allowed in the following
+escapes: `\A', `\B', `\Z', `\C', and `\w'.
+
+   Finally, the escapes `\D', `\h', `\H', `\l', `\L', `\N', `\R', `\s',
+`\S', `\v', and `\x' can't use the following characters as delimiters:
+
+   * The digits `0'-`9'.
+
+   * The (single-character) operators `+-/*%<>=&:().'.
+
+   * The space, tab, and newline characters.
+
+   * All escape sequences except `\%', `\:', `\{', `\}', `\'', `\`',
+     `\-', `\_', `\!', `\@', `\/', `\c', `\e', and `\p'.
+
+   To have a backslash (actually, the current escape character) appear
+in the output several escapes are defined: `\\', `\e' or `\E'.  These
+are very similar, and only differ with respect to being used in macros
+or diversions.  *Note Character Translations::, for an exact
+description of those escapes.
+
+   *Note Implementation Differences::, *Note Copy-in Mode::, and *Note
+Diversions::, *Note Identifiers::, for more information.
+
+* Menu:
+
+* Comments::
+
+
+File: groff,  Node: Comments,  Prev: Escapes,  Up: Escapes
+
+5.5.3.1 Comments
+................
+
+Probably one of the most(1) (*note Comments-Footnote-1::) common forms
+of escapes is the comment.
+
+ -- Escape: \"
+     Start a comment.  Everything to the end of the input line is
+     ignored.
+
+     This may sound simple, but it can be tricky to keep the comments
+     from interfering with the appearance of the final output.
+
+     If the escape is to the right of some text or a request, that
+     portion of the line is ignored, but the space leading up to it is
+     noticed by `gtroff'.  This only affects the `ds' and `as' request
+     and its variants.
+
+     One possibly irritating idiosyncracy is that tabs must not be used
+     to line up comments.  Tabs are not treated as whitespace between
+     the request and macro arguments.
+
+     A comment on a line by itself is treated as a blank line, because
+     after eliminating the comment, that is all that remains:
+
+
+          Test
+          \" comment
+          Test
+
+     produces
+
+
+          Test
+
+          Test
+
+     To avoid this, it is common to start the line with `.\"' which
+     causes the line to be treated as an undefined request and thus
+     ignored completely.
+
+     Another commenting scheme seen sometimes is three consecutive
+     single quotes (`'''') at the beginning of a line.  This works, but
+     `gtroff' gives a warning about an undefined macro (namely `'''),
+     which is harmless, but irritating.
+
+ -- Escape: \#
+     To avoid all this, `gtroff' has a new comment mechanism using the
+     `\#' escape.  This escape works the same as `\"' except that the
+     newline is also ignored:
+
+
+          Test
+          \# comment
+          Test
+
+     produces
+
+
+          Test Test
+
+     as expected.
+
+ -- Request: .ig [end]
+     Ignore all input until `gtroff' encounters the macro named `.'END
+     on a line by itself (or `..' if END is not specified).  This is
+     useful for commenting out large blocks of text:
+
+
+          text text text...
+          .ig
+          This is part of a large block
+          of text that has been
+          temporarily(?) commented out.
+
+          We can restore it simply by removing
+          the .ig request and the ".." at the
+          end of the block.
+          ..
+          More text text text...
+
+     produces
+
+
+          text text text...  More text text text...
+
+     Note that the commented-out block of text does not cause a break.
+
+     The input is read in copy-mode; auto-incremented registers _are_
+     affected (*note Auto-increment::).
+
+
+File: groff,  Node: Comments-Footnotes,  Up: Comments
+
+   (1) Unfortunately, this is a lie.  But hopefully future `gtroff'
+hackers will believe it `:-)'
+
+
+File: groff,  Node: Registers,  Next: Manipulating Filling and Adjusting,  Prev: Embedded Commands,  Up: gtroff Reference
+
+5.6 Registers
+=============
+
+Numeric variables in `gtroff' are called "registers".  There are a
+number of built-in registers, supplying anything from the date to
+details of formatting parameters.
+
+   *Note Identifiers::, for details on register identifiers.
+
+* Menu:
+
+* Setting Registers::
+* Interpolating Registers::
+* Auto-increment::
+* Assigning Formats::
+* Built-in Registers::
+
+
+File: groff,  Node: Setting Registers,  Next: Interpolating Registers,  Prev: Registers,  Up: Registers
+
+5.6.1 Setting Registers
+-----------------------
+
+Define or set registers using the `nr' request or the `\R' escape.
+
+ -- Request: .nr ident value
+ -- Escape: \R'ident value'
+     Set number register IDENT to VALUE.  If IDENT doesn't exist,
+     `gtroff' creates it.
+
+     The argument to `\R' usually has to be enclosed in quotes.  *Note
+     Escapes::, for details on parameter delimiting characters.
+
+     The `\R' escape doesn't produce an input token in `gtroff'; with
+     other words, it vanishes completely after `gtroff' has processed
+     it.
+
+   For example, the following two lines are equivalent:
+
+
+     .nr a (((17 + (3 * 4))) % 4)
+     \R'a (((17 + (3 * 4))) % 4)'
+         => 1
+
+   Both `nr' and `\R' have two additional special forms to increment or
+decrement a register.
+
+ -- Request: .nr ident +value
+ -- Request: .nr ident -value
+ -- Escape: \R'ident +value'
+ -- Escape: \R'ident -value'
+     Increment (decrement) register IDENT by VALUE.
+
+
+          .nr a 1
+          .nr a +1
+          \na
+              => 2
+
+     To assign the negated value of a register to another register,
+     some care must be taken to get the desired result:
+
+
+          .nr a 7
+          .nr b 3
+          .nr a -\nb
+          \na
+              => 4
+          .nr a (-\nb)
+          \na
+              => -3
+
+     The surrounding parentheses prevent the interpretation of the
+     minus sign as a decrementing operator.  An alternative is to start
+     the assignment with a `0':
+
+
+          .nr a 7
+          .nr b -3
+          .nr a \nb
+          \na
+              => 4
+          .nr a 0\nb
+          \na
+              => -3
+
+
+ -- Request: .rr ident
+     Remove number register IDENT.  If IDENT doesn't exist, the request
+     is ignored.
+
+ -- Request: .rnn ident1 ident2
+     Rename number register IDENT1 to IDENT2.  If either IDENT1 or
+     IDENT2 doesn't exist, the request is ignored.
+
+ -- Request: .aln ident1 ident2
+     Create an alias IDENT1 for a number register IDENT2.  The new name
+     and the old name are exactly equivalent.  If IDENT1 is undefined,
+     a warning of type `reg' is generated, and the request is ignored.
+     *Note Debugging::, for information about warnings.
+
+
+File: groff,  Node: Interpolating Registers,  Next: Auto-increment,  Prev: Setting Registers,  Up: Registers
+
+5.6.2 Interpolating Registers
+-----------------------------
+
+Numeric registers can be accessed via the `\n' escape.
+
+ -- Escape: \ni
+ -- Escape: \n(id
+ -- Escape: \n[ident]
+     Interpolate number register with name IDENT (one-character name I,
+     two-character name ID).  This means that the value of the register
+     is expanded in-place while `gtroff' is parsing the input line.
+     Nested assignments (also called indirect assignments) are possible.
+
+
+          .nr a 5
+          .nr as \na+\na
+          \n(as
+              => 10
+
+
+          .nr a1 5
+          .nr ab 6
+          .ds str b
+          .ds num 1
+          \n[a\n[num]]
+              => 5
+          \n[a\*[str]]
+              => 6
+
+
+
+File: groff,  Node: Auto-increment,  Next: Assigning Formats,  Prev: Interpolating Registers,  Up: Registers
+
+5.6.3 Auto-increment
+--------------------
+
+Number registers can also be auto-incremented and auto-decremented.
+The increment or decrement value can be specified with a third argument
+to the `nr' request or `\R' escape.
+
+ -- Request: .nr ident value incr
+     Set number register IDENT to VALUE; the increment for
+     auto-incrementing is set to INCR.  Note that the `\R' escape
+     doesn't support this notation.
+
+   To activate auto-incrementing, the escape `\n' has a special syntax
+form.
+
+ -- Escape: \n+i
+ -- Escape: \n-i
+ -- Escape: \n(+id
+ -- Escape: \n(-id
+ -- Escape: \n+(id
+ -- Escape: \n-(id
+ -- Escape: \n[+ident]
+ -- Escape: \n[-ident]
+ -- Escape: \n+[ident]
+ -- Escape: \n-[ident]
+     Before interpolating, increment or decrement IDENT (one-character
+     name I, two-character name ID) by the auto-increment value as
+     specified with the `nr' request (or the `\R' escape).  If no
+     auto-increment value has been specified, these syntax forms are
+     identical to `\n'.
+
+   For example,
+
+
+     .nr a 0 1
+     .nr xx 0 5
+     .nr foo 0 -2
+     \n+a, \n+a, \n+a, \n+a, \n+a
+     .br
+     \n-(xx, \n-(xx, \n-(xx, \n-(xx, \n-(xx
+     .br
+     \n+[foo], \n+[foo], \n+[foo], \n+[foo], \n+[foo]
+
+produces
+
+
+     1, 2, 3, 4, 5
+     -5, -10, -15, -20, -25
+     -2, -4, -6, -8, -10
+
+   To change the increment value without changing the value of a
+register (A in the example), the following can be used:
+
+
+     .nr a \na 10
+
+
+File: groff,  Node: Assigning Formats,  Next: Built-in Registers,  Prev: Auto-increment,  Up: Registers
+
+5.6.4 Assigning Formats
+-----------------------
+
+When a register is used in the text of an input file (as opposed to
+part of an expression), it is textually replaced (or interpolated) with
+a representation of that number.  This output format can be changed to
+a variety of formats (numbers, Roman numerals, etc.).  This is done
+using the `af' request.
+
+ -- Request: .af ident format
+     Change the output format of a number register.  The first argument
+     IDENT is the name of the number register to be changed, and the
+     second argument FORMAT is the output format.  The following output
+     formats are available:
+
+    `1'
+          Decimal arabic numbers.  This is the default format: 0, 1, 2,
+          3, ....
+
+    `0...0'
+          Decimal numbers with as many digits as specified.  So, `00'
+          would result in printing numbers as 01, 02, 03, ....
+
+          In fact, any digit instead of zero will do; `gtroff' only
+          counts how many digits are specified.  As a consequence,
+          `af''s default format `1' could be specified as `0' also (and
+          exactly this is returned by the `\g' escape, see below).
+
+    `I'
+          Upper-case Roman numerals: 0, I, II, III, IV, ....
+
+    `i'
+          Lower-case Roman numerals: 0, i, ii, iii, iv, ....
+
+    `A'
+          Upper-case letters: 0, A, B, C, ..., Z, AA, AB, ....
+
+    `a'
+          Lower-case letters: 0, a, b, c, ..., z, aa, ab, ....
+
+     Omitting the number register format causes a warning of type
+     `missing'.  *Note Debugging::, for more details.  Specifying a
+     nonexistent format causes an error.
+
+     The following example produces `10, X, j, 010':
+
+
+          .nr a 10
+          .af a 1           \" the default format
+          \na,
+          .af a I
+          \na,
+          .af a a
+          \na,
+          .af a 001
+          \na
+
+     The largest number representable for the `i' and `I' formats is
+     39999 (or -39999); UNIX `troff' uses `z' and `w' to represent
+     10000 and 5000 in Roman numerals, and so does `gtroff'.
+     Currently, the correct glyphs of Roman numeral five thousand and
+     Roman numeral ten thousand (Unicode code points `U+2182' and
+     `U+2181', respectively) are not available.
+
+     If IDENT doesn't exist, it is created.
+
+     Changing the output format of a read-only register causes an
+     error.  It is necessary to first copy the register's value to a
+     writeable register, then apply the `af' request to this other
+     register.
+
+ -- Escape: \gi
+ -- Escape: \g(id
+ -- Escape: \g[ident]
+     Return the current format of the specified register IDENT
+     (one-character name I, two-character name ID).  For example, `\ga'
+     after the previous example would produce the string `000'.  If the
+     register hasn't been defined yet, nothing is returned.
+
+
+File: groff,  Node: Built-in Registers,  Prev: Assigning Formats,  Up: Registers
+
+5.6.5 Built-in Registers
+------------------------
+
+The following lists some built-in registers which are not described
+elsewhere in this manual.  Any register which begins with a `.' is
+read-only.  A complete listing of all built-in registers can be found in
+*Note Register Index::.
+
+`\n[.F]'
+     This string-valued register returns the current input file name.
+
+`\n[.H]'
+     Horizontal resolution in basic units.
+
+`\n[.U]'
+     If `gtroff' is called with the `-U' command line option, the
+     number register `.U' is set to 1, and zero otherwise.  *Note Groff
+     Options::.
+
+`\n[.V]'
+     Vertical resolution in basic units.
+
+`\n[seconds]'
+     The number of seconds after the minute, normally in the range 0
+     to 59, but can be up to 61 to allow for leap seconds.  Initialized
+     at start-up of `gtroff'.
+
+`\n[minutes]'
+     The number of minutes after the hour, in the range 0 to 59.
+     Initialized at start-up of `gtroff'.
+
+`\n[hours]'
+     The number of hours past midnight, in the range 0 to 23.
+     Initialized at start-up of `gtroff'.
+
+`\n[dw]'
+     Day of the week (1-7).
+
+`\n[dy]'
+     Day of the month (1-31).
+
+`\n[mo]'
+     Current month (1-12).
+
+`\n[year]'
+     The current year.
+
+`\n[yr]'
+     The current year minus 1900.  Unfortunately, the documentation of
+     UNIX Version 7's `troff' had a year 2000 bug: It incorrectly
+     claimed that `yr' contains the last two digits of the year.  That
+     claim has never been true of either AT&T `troff' or GNU `troff'.
+     Old `troff' input that looks like this:
+
+
+          '\" The following line stopped working after 1999
+          This document was formatted in 19\n(yr.
+
+     can be corrected as follows:
+
+
+          This document was formatted in \n[year].
+
+     or, to be portable to older `troff' versions, as follows:
+
+
+          .nr y4 1900+\n(yr
+          This document was formatted in \n(y4.
+
+`\n[.c]'
+`\n[c.]'
+     The current _input_ line number.  Register `.c' is read-only,
+     whereas `c.' (a `gtroff' extension) is writable also, affecting
+     both `.c' and `c.'.
+
+`\n[ln]'
+     The current _output_ line number after a call to the `nm' request
+     to activate line numbering.
+
+     *Note Miscellaneous::, for more information about line numbering.
+
+`\n[.x]'
+     The major version number.  For example, if the version number is
+     1.03 then `.x' contains `1'.
+
+`\n[.y]'
+     The minor version number.  For example, if the version number is
+     1.03 then `.y' contains `03'.
+
+`\n[.Y]'
+     The revision number of `groff'.
+
+`\n[$$]'
+     The process ID of `gtroff'.
+
+`\n[.g]'
+     Always 1.  Macros should use this to determine whether they are
+     running under GNU `troff'.
+
+`\n[.A]'
+     If the command line option `-a' is used to produce an ASCII
+     approximation of the output, this is set to 1, zero otherwise.
+     *Note Groff Options::.
+
+`\n[.P]'
+     This register is set to 1 (and to 0 otherwise) if the current page
+     is actually being printed, i.e., if the `-o' option is being used
+     to only print selected pages.  *Note Groff Options::, for more
+     information.
+
+`\n[.T]'
+     If `gtroff' is called with the `-T' command line option, the
+     number register `.T' is set to 1, and zero otherwise.  *Note Groff
+     Options::.
+
+`\*[.T]'
+     A single read-write string register which contains the current
+     output device (for example, `latin1' or `ps').  This is the only
+     string register defined by `gtroff'.
+
+
+File: groff,  Node: Manipulating Filling and Adjusting,  Next: Manipulating Hyphenation,  Prev: Registers,  Up: gtroff Reference
+
+5.7 Manipulating Filling and Adjusting
+======================================
+
+Various ways of causing "breaks" were given in *Note Implicit Line
+Breaks::.  The `br' request likewise causes a break.  Several other
+requests also cause breaks, but implicitly.  These are `bp', `ce',
+`cf', `fi', `fl', `in', `nf', `rj', `sp', `ti', and `trf'.
+
+ -- Request: .br
+     Break the current line, i.e., the input collected so far is emitted
+     without adjustment.
+
+     If the no-break control character is used, `gtroff' suppresses the
+     break:
+
+
+          a
+          'br
+          b
+              => a b
+
+
+   Initially, `gtroff' fills and adjusts text to both margins.  Filling
+can be disabled via the `nf' request and re-enabled with the `fi'
+request.
+
+ -- Request: .fi
+ -- Register: \n[.u]
+     Activate fill mode (which is the default).  This request implicitly
+     enables adjusting; it also inserts a break in the text currently
+     being filled.  The read-only number register `.u' is set to 1.
+
+     The fill mode status is associated with the current environment
+     (*note Environments::).
+
+     See *Note Line Control::, for interaction with the `\c' escape.
+
+ -- Request: .nf
+     Activate no-fill mode.  Input lines are output as-is, retaining
+     line breaks and ignoring the current line length.  This command
+     implicitly disables adjusting; it also causes a break.  The number
+     register `.u' is set to 0.
+
+     The fill mode status is associated with the current environment
+     (*note Environments::).
+
+     See *Note Line Control::, for interaction with the `\c' escape.
+
+ -- Request: .ad [mode]
+ -- Register: \n[.j]
+     Set adjusting mode.
+
+     Activation and deactivation of adjusting is done implicitly with
+     calls to the `fi' or `nf' requests.
+
+     MODE can have one of the following values:
+
+    `l'
+          Adjust text to the left margin.  This produces what is
+          traditionally called ragged-right text.
+
+    `r'
+          Adjust text to the right margin, producing ragged-left text.
+
+    `c'
+          Center filled text.  This is different to the `ce' request
+          which only centers text without filling.
+
+    `b'
+    `n'
+          Justify to both margins.  This is the default used by
+          `gtroff'.
+
+     Finally, MODE can be the numeric argument returned by the `.j'
+     register.
+
+     With no argument, `gtroff' adjusts lines in the same way it did
+     before adjusting was deactivated (with a call to `na', for
+     example).
+
+
+          text
+          .ad r
+          .nr ad \n[.j]
+          text
+          .ad c
+          text
+          .na
+          text
+          .ad         \" back to centering
+          text
+          .ad \n[ad]  \" back to right justifying
+
+     The current adjustment mode is available in the read-only number
+     register `.j'; it can be stored and subsequently used to set
+     adjustment.
+
+     The adjustment mode status is associated with the current
+     environment (*note Environments::).
+
+ -- Request: .na
+     Disable adjusting.  This request won't change the current
+     adjustment mode: A subsequent call to `ad' uses the previous
+     adjustment setting.
+
+     The adjustment mode status is associated with the current
+     environment (*note Environments::).
+
+ -- Request: .brp
+ -- Escape: \p
+     Adjust the current line and cause a break.
+
+     In most cases this produces very ugly results since `gtroff'
+     doesn't have a sophisticated paragraph building algorithm (as TeX
+     have, for example); instead, `gtroff' fills and adjusts a paragraph
+     line by line:
+
+
+            This is an uninteresting sentence.
+            This is an uninteresting sentence.\p
+            This is an uninteresting sentence.
+
+     is formatted as
+
+
+            This is  an uninteresting  sentence.   This  is an
+            uninteresting                            sentence.
+            This is an uninteresting sentence.
+
+
+ -- Request: .ss word_space_size [sentence_space_size]
+ -- Register: \n[.ss]
+ -- Register: \n[.sss]
+     Change the size of a space between words.  It takes its units as
+     one twelfth of the space width parameter for the current font.
+     Initially both the WORD_SPACE_SIZE and SENTENCE_SPACE_SIZE are 12.
+     In fill mode, the values specify the minimum distance.
+
+     If two arguments are given to the `ss' request, the second
+     argument sets the sentence space size.  If the second argument is
+     not given, sentence space size is set to WORD_SPACE_SIZE.  The
+     sentence space size is used in two circumstances: If the end of a
+     sentence occurs at the end of a line in fill mode, then both an
+     inter-word space and a sentence space are added; if two spaces
+     follow the end of a sentence in the middle of a line, then the
+     second space is a sentence space.  If a second argument is never
+     given to the `ss' request, the behaviour of UNIX `troff' is the
+     same as that exhibited by GNU `troff'.  In GNU `troff', as in UNIX
+     `troff', a sentence should always be followed by either a newline
+     or two spaces.
+
+     The read-only number registers `.ss' and `.sss' hold the values of
+     the parameters set by the first and second arguments of the `ss'
+     request.
+
+     The word space and sentence space values are associated with the
+     current environment (*note Environments::).
+
+     Contrary to AT&T `troff', this request is _not_ ignored if a TTY
+     output device is used; the given values are then rounded down to a
+     multiple of 12 (*note Implementation Differences::).
+
+     The request is ignored if there is no parameter.
+
+     Another useful application of the `ss' request is to insert
+     discardable horizontal space, i.e., space which is discarded at a
+     line break.  For example, paragraph-style footnotes could be
+     separated this way:
+
+
+          .ll 4.5i
+          1.\ This is the first footnote.\c
+          .ss 48
+          .nop
+          .ss 12
+          2.\ This is the second footnote.
+
+     The result:
+
+
+          1. This is the first footnote.        2. This
+          is the second footnote.
+
+     Note that the `\h' escape produces unbreakable space.
+
+ -- Request: .ce [nnn]
+ -- Register: \n[.ce]
+     Center text.  While the `.ad c' request also centers text, it
+     fills the text as well.  `ce' does not fill the text it affects.
+     This request causes a break.  The number of lines still to be
+     centered is associated with the current environment (*note
+     Environments::).
+
+     The following example demonstrates the differences.  Here the
+     input:
+
+
+          .ll 4i
+          .ce 1000
+          This is a small text fragment which shows the differences
+          between the `.ce' and the `.ad c' request.
+          .ce 0
+
+          .ad c
+          This is a small text fragment which shows the differences
+          between the `.ce' and the `.ad c' request.
+
+     And here the result:
+
+
+            This is a small text fragment which
+                   shows the differences
+          between the `.ce' and the `.ad c' request.
+
+            This is a small text fragment which
+          shows the differences between the `.ce'
+                  and the `.ad c' request.
+
+     With no arguments, `ce' centers the next line of text.  NNN
+     specifies the number of lines to be centered.  If the argument is
+     zero or negative, centering is disabled.
+
+     The basic length for centering text is the line length (as set
+     with the `ll' request) minus the indentation (as set with the `in'
+     request).  Temporary indentation is ignored.
+
+     As can be seen in the previous example, it is a common idiom to
+     turn on centering for a large number of lines, and to turn off
+     centering after text to be centered.  This is useful for any
+     request which takes a number of lines as an argument.
+
+     The `.ce' read-only number register contains the number of lines
+     remaining to be centered, as set by the `ce' request.
+
+ -- Request: .rj [nnn]
+ -- Register: \n[.rj]
+     Justify unfilled text to the right margin.  Arguments are
+     identical to the `ce' request.  The `.rj' read-only number
+     register is the number of lines to be right-justified as set by
+     the `rj' request.  This request causes a break.  The number of
+     lines still to be right-justified is associated with the current
+     environment (*note Environments::).
+
+
+File: groff,  Node: Manipulating Hyphenation,  Next: Manipulating Spacing,  Prev: Manipulating Filling and Adjusting,  Up: gtroff Reference
+
+5.8 Manipulating Hyphenation
+============================
+
+Here a description of requests which influence hyphenation.
+
+ -- Request: .hy [mode]
+ -- Register: \n[.hy]
+     Enable hyphenation.  The request has an optional numeric argument,
+     MODE, to restrict hyphenation if necessary:
+
+    `1'
+          The default argument if MODE is omitted.  Hyphenate without
+          restrictions.  This is also the start-up value of `gtroff'.
+
+    `2'
+          Do not hyphenate the last word on a page or column.
+
+    `4'
+          Do not hyphenate the last two characters of a word.
+
+    `8'
+          Do not hyphenate the first two characters of a word.
+
+     Values in the previous table are additive.  For example, the
+     value 12 causes `gtroff' to neither hyphenate the last two nor the
+     first two characters of a word.
+
+     The current hyphenation restrictions can be found in the read-only
+     number register `.hy'.
+
+     The hyphenation mode is associated with the current environment
+     (*note Environments::).
+
+ -- Request: .nh
+     Disable hyphenation (i.e., set the hyphenation mode to zero).  Note
+     that the hyphenation mode of the last call to `hy' is not
+     remembered.
+
+     The hyphenation mode is associated with the current environment
+     (*note Environments::).
+
+ -- Request: .hlm [nnn]
+ -- Register: \n[.hlm]
+ -- Register: \n[.hlc]
+     Set the maximum number of consecutive hyphenated lines to NNN.  If
+     this number is negative, there is no maximum.  The default value
+     is -1 if NNN is omitted.  This value is associated with the
+     current environment (*note Environments::).  Only lines output
+     from a given environment count towards the maximum associated with
+     that environment.  Hyphens resulting from `\%' are counted;
+     explicit hyphens are not.
+
+     The current setting of `hlm' is available in the `.hlm' read-only
+     number register.  Also the number of immediately preceding
+     consecutive hyphenated lines are available in the read-only number
+     register `.hlc'.
+
+ -- Request: .hw word1 word2 ...
+     Define how WORD1, WORD2, etc. are to be hyphenated.  The words
+     must be given with hyphens at the hyphenation points.  For example:
+
+
+          .hw in-sa-lub-rious
+
+     Besides the space character, any character whose hyphenation code
+     value is zero can be used to separate the arguments of `hw' (see
+     the documentation for the `hcode' request below for more
+     information).  In addition, this request can be used more than
+     once.
+
+     Hyphenation exceptions specified with the `hw' request are
+     associated with the current hyphenation language; it causes an
+     error if there is no current hyphenation language.
+
+     This request is ignored if there is no parameter.
+
+     In old versions of `troff' there was a limited amount of space to
+     store such information; fortunately, with `gtroff', this is no
+     longer a restriction.
+
+ -- Escape: \%
+ -- Escape: \:
+     To tell `gtroff' how to hyphenate words on the fly, use the `\%'
+     escape, also known as the "hyphenation character".  Preceding a
+     word with this character prevents it from being hyphenated;
+     putting it inside a word indicates to `gtroff' that the word may
+     be hyphenated at that point.  Note that this mechanism only
+     affects that one occurrence of the word; to change the hyphenation
+     of a word for the entire document, use the `hw' request.
+
+     The `\:' escape inserts a zero-width break point (that is, the
+     word breaks but without adding a hyphen).
+
+
+          ... check the /var/log/\:httpd/\:access_log file ...
+
+     Note that `\X' and `\Y' start a word, that is, the `\%' escape in
+     (say) `\X'...'\%foobar' and `\Y'...'\%foobar' no longer prevents
+     hyphenation but inserts a hyphenation point at the beginning of
+     `foobar'; most likely this isn't what you want to do.
+
+ -- Request: .hc [char]
+     Change the hyphenation character to CHAR.  This character then
+     works the same as the `\%' escape, and thus, no longer appears in
+     the output.  Without an argument, `hc' resets the hyphenation
+     character to be `\%' (the default) only.
+
+     The hyphenation character is associated with the current
+     environment (*note Environments::).
+
+ -- Request: .hpf pattern_file
+ -- Request: .hpfa pattern_file
+ -- Request: .hpfcode a b [c d ...]
+     Read in a file of hyphenation patterns.  This file is searched for
+     in the same way as `NAME.tmac' (or `tmac.NAME') is searched for if
+     the `-mNAME' option is specified.
+
+     It should have the same format as (simple) TeX patterns files.
+     More specifically, the following scanning rules are implemented.
+
+        * A percent sign starts a comment (up to the end of the line)
+          even if preceded by a backslash.
+
+        * No support for `digraphs' like `\$'.
+
+        * `^^XX' (X is 0-9 or a-f) and `^^X' (character code of X in
+          the range 0-127) are recognized; other use of `^' causes an
+          error.
+
+        * No macro expansion.
+
+        * `hpf' checks for the expression `\patterns{...}' (possibly
+          with whitespace before and after the braces).  Everything
+          between the braces is taken as hyphenation patterns.
+          Consequently, `{' and `}' are not allowed in patterns.
+
+        * Similarly, `\hyphenation{...}' gives a list of hyphenation
+          exceptions.
+
+        * `\endinput' is recognized also.
+
+        * For backwards compatibility, if `\patterns' is missing, the
+          whole file is treated as a list of hyphenation patterns (only
+          recognizing the `%' character as the start of a comment).
+
+     If no `hpf' request is specified (either in the document or in a
+     macro package), `gtroff' won't hyphenate at all.
+
+     The `hpfa' request appends a file of patterns to the current list.
+
+     The `hpfcode' request defines mapping values for character codes in
+     hyphenation patterns.  `hpf' or `hpfa' then apply the mapping
+     (after reading the patterns) before replacing or appending them to
+     the current list of patterns.  Its arguments are pairs of
+     character codes - integers from 0 to 255.  The request maps
+     character code A to code B, code C to code D, and so on.  You can
+     use character codes which would be invalid otherwise.
+
+     The set of hyphenation patterns is associated with the current
+     language set by the `hla' request.  The `hpf' request is usually
+     invoked by the `troffrc' or `troffrc-end' file; by default,
+     `troffrc' loads hyphenation patterns and exceptions for American
+     English (in files `hyphen.us' and `hyphenex.us').
+
+     A second call to `hpf' (for the same language) will replace the
+     hyphenation patterns with the new ones.
+
+     Invoking `hpf' causes an error if there is no current hyphenation
+     language.
+
+ -- Request: .hcode c1 code1 [c2 code2 ...]
+     Set the hyphenation code of character C1 to CODE1, that of C2 to
+     CODE2, etc.  A hyphenation code must be a single input character
+     (not a special character) other than a digit or a space.
+
+     To make hyphenation work, hyphenation codes must be set up.  At
+     start-up, groff only assigns hyphenation codes to the letters
+     `a'-`z' (mapped to themselves) and to the letters `A'-`Z' (mapped
+     to `a'-`z'); all other hyphenation codes are set to zero.
+     Normally, hyphenation patterns contain only lowercase letters
+     which should be applied regardless of case.  With other words, the
+     words `FOO' and `Foo' should be hyphenated exactly the same way as
+     the word `foo' is hyphenated, and this is what `hcode' is good
+     for.  Words which contain other letters won't be hyphenated
+     properly if the corresponding hyphenation patterns actually do
+     contain them.  For example, the following `hcode' requests are
+     necessary to assign hyphenation codes to the letters `ÄäÖöÜüß'
+     (this is needed for German):
+
+
+          .hcode ä ä  Ä ä
+          .hcode ö ö  Ö ö
+          .hcode ü ü  Ü ü
+          .hcode ß ß
+
+     Without those assignments, groff treats German words like
+     `Kindergärten' (the plural form of `kindergarten') as two
+     substrings `kinderg' and `rten' because the hyphenation code of
+     the umlaut a is zero by default.  There is a German hyphenation
+     pattern which covers `kinder', so groff finds the hyphenation
+     `kin-der'.  The other two hyphenation points (`kin-der-gär-ten')
+     are missed.
+
+     This request is ignored if it has no parameter.
+
+ -- Request: .hym [length]
+ -- Register: \n[.hym]
+     Set the (right) hyphenation margin to LENGTH.  If the current
+     adjustment mode is not `b' or `n', the line is not hyphenated if
+     it is shorter than LENGTH.  Without an argument, the hyphenation
+     margin is reset to its default value, which is 0.  The default
+     scaling indicator for this request is `m'.  The hyphenation margin
+     is associated with the current environment (*note Environments::).
+
+     A negative argument resets the hyphenation margin to zero, emitting
+     a warning of type `range'.
+
+     The current hyphenation margin is available in the `.hym' read-only
+     number register.
+
+ -- Request: .hys [hyphenation_space]
+ -- Register: \n[.hys]
+     Set the hyphenation space to HYPHENATION_SPACE.  If the current
+     adjustment mode is `b' or `n', don't hyphenate the line if it can
+     be justified by adding no more than HYPHENATION_SPACE extra space
+     to each word space.  Without argument, the hyphenation space is
+     set to its default value, which is 0.  The default scaling
+     indicator for this request is `m'.  The hyphenation space is
+     associated with the current environment (*note Environments::).
+
+     A negative argument resets the hyphenation space to zero, emitting
+     a warning of type `range'.
+
+     The current hyphenation space is available in the `.hys' read-only
+     number register.
+
+ -- Request: .shc [glyph]
+     Set the "soft hyphen character" to GLYPH.(1) (*note Manipulating
+     Hyphenation-Footnote-1::)  If the argument is omitted, the soft
+     hyphen character is set to the default glyph `\(hy' (this is the
+     start-up value of `gtroff' also).  The soft hyphen character is
+     the glyph that is inserted when a word is hyphenated at a line
+     break.  If the soft hyphen character does not exist in the font of
+     the character immediately preceding a potential break point, then
+     the line is not broken at that point.  Neither definitions
+     (specified with the `char' request) nor translations (specified
+     with the `tr' request) are considered when finding the soft hyphen
+     character.
+
+ -- Request: .hla language
+ -- Register: \n[.hla]
+     Set the current hyphenation language to the string LANGUAGE.
+     Hyphenation exceptions specified with the `hw' request and
+     hyphenation patterns specified with the `hpf' and `hpfa' requests
+     are both associated with the current hyphenation language.  The
+     `hla' request is usually invoked by the `troffrc' or the
+     `troffrc-end' files; `troffrc' sets the default language to `us'.
+
+     The current hyphenation language is available as a string in the
+     read-only number register `.hla'.
+
+
+          .ds curr_language \n[.hla]
+          \*[curr_language]
+              => us
+
+
+
+File: groff,  Node: Manipulating Hyphenation-Footnotes,  Up: Manipulating Hyphenation
+
+   (1) "Soft hyphen character" is a misnomer since it is an output
+glyph.
+
+
+File: groff,  Node: Manipulating Spacing,  Next: Tabs and Fields,  Prev: Manipulating Hyphenation,  Up: gtroff Reference
+
+5.9 Manipulating Spacing
+========================
+
+ -- Request: .sp [distance]
+     Space downwards DISTANCE.  With no argument it advances 1 line.  A
+     negative argument causes `gtroff' to move up the page the
+     specified distance.  If the argument is preceded by a `|' then
+     `gtroff' moves that distance from the top of the page.  This
+     request causes a line break.  The default scaling indicator is `v'.
+
+     If a vertical trap is sprung during execution of `sp', the amount
+     of vertical space after the trap is discarded.  For example, this
+
+
+          .de xxx
+          ..
+          .
+          .wh 0 xxx
+          .
+          .pl 5v
+          foo
+          .sp 2
+          bar
+          .sp 50
+          baz
+
+     results in
+
+
+          foo
+
+
+          bar
+
+          baz
+
+     The amount of discarded space is available in the number register
+     `.trunc'.
+
+     To protect `sp' against vertical traps, use the `vpt' request:
+
+
+          .vpt 0
+          .sp -3
+          .vpt 1
+
+
+ -- Request: .ls [nnn]
+ -- Register: \n[.L]
+     Output NNN-1 blank lines after each line of text.  With no
+     argument, `gtroff' uses the previous value before the last `ls'
+     call.
+
+
+          .ls 2    \" This causes double-spaced output
+          .ls 3    \" This causes triple-spaced output
+          .ls      \" Again double-spaced
+
+     The line spacing is associated with the current environment (*note
+     Environments::).
+
+     The read-only number register `.L' contains the current line
+     spacing setting.
+
+   *Note Changing Type Sizes::, for the requests `vs' and `pvs' as
+alternatives to `ls'.
+
+ -- Escape: \x'spacing'
+ -- Register: \n[.a]
+     Sometimes, extra vertical spacing is only needed occasionally, e.g.
+     to allow space for a tall construct (like an equation).  The `\x'
+     escape does this.  The escape is given a numerical argument,
+     usually enclosed in quotes (like `\x'3p''); the default scaling
+     indicator is `v'.  If this number is positive extra vertical space
+     is inserted below the current line.  A negative number adds space
+     above.  If this escape is used multiple times on the same line,
+     the maximum of the values is used.
+
+     *Note Escapes::, for details on parameter delimiting characters.
+
+     The `.a' read-only number register contains the most recent
+     (nonnegative) extra vertical line space.
+
+     Using `\x' can be necessary in combination with the `\b' escape,
+     as the following example shows.
+
+
+          This is a test with the \[rs]b escape.
+          .br
+          This is a test with the \[rs]b escape.
+          .br
+          This is a test with \b'xyz'\x'-1m'\x'1m'.
+          .br
+          This is a test with the \[rs]b escape.
+          .br
+          This is a test with the \[rs]b escape.
+
+     produces
+
+
+          This is a test with the \b escape.
+          This is a test with the \b escape.
+                              x
+          This is a test with y.
+                              z
+          This is a test with the \b escape.
+          This is a test with the \b escape.
+
+
+ -- Request: .ns
+ -- Request: .rs
+ -- Register: \n[.ns]
+     Enable "no-space mode".  In this mode, spacing (either via `sp' or
+     via blank lines) is disabled.  The `bp' request to advance to the
+     next page is also disabled, except if it is accompanied by a page
+     number (see *Note Page Control::, for more information).  This
+     mode ends when actual text is output or the `rs' request is
+     encountered which ends no-space mode.  The read-only number
+     register `.ns' is set to 1 as long as no-space mode is active.
+
+     This request is useful for macros that conditionally insert
+     vertical space before the text starts (for example, a paragraph
+     macro could insert some space except when it is the first
+     paragraph after a section header).
+
+
+File: groff,  Node: Tabs and Fields,  Next: Character Translations,  Prev: Manipulating Spacing,  Up: gtroff Reference
+
+5.10 Tabs and Fields
+====================
+
+A tab character (ASCII char 9, EBCDIC char 5) causes a horizontal
+movement to the next tab stop (much like it did on a typewriter).
+
+ -- Escape: \t
+     This escape is a non-interpreted tab character.  In copy mode
+     (*note Copy-in Mode::), `\t' is the same as a real tab character.
+
+ -- Request: .ta [n1 n2 ... nn T r1 r2 ... rn]
+ -- Register: \n[.tabs]
+     Change tab stop positions.  This request takes a series of tab
+     specifiers as arguments (optionally divided into two groups with
+     the letter `T') which indicate where each tab stop is to be
+     (overriding any previous settings).
+
+     Tab stops can be specified absolutely, i.e., as the distance from
+     the left margin.  For example, the following sets 6 tab stops every
+     one inch.
+
+
+          .ta 1i 2i 3i 4i 5i 6i
+
+     Tab stops can also be specified using a leading `+' which means
+     that the specified tab stop is set relative to the previous tab
+     stop.  For example, the following is equivalent to the previous
+     example.
+
+
+          .ta 1i +1i +1i +1i +1i +1i
+
+     `gtroff' supports an extended syntax to specify repeat values after
+     the `T' mark (these values are always taken as relative) - this is
+     the usual way to specify tabs set at equal intervals.  The
+     following is, yet again, the same as the previous examples.  It
+     does even more since it defines an infinite number of tab stops
+     separated by one inch.
+
+
+          .ta T 1i
+
+     Now we are ready to interpret the full syntax given at the
+     beginning: Set tabs at positions N1, N2, ..., NN and then set tabs
+     at NN+R1, NN+R2, ..., NN+RN and then at NN+RN+R1, NN+RN+R2, ...,
+     NN+RN+RN, and so on.
+
+     Example: `4c +6c T 3c 5c 2c' is equivalent to `4c 10c 13c 18c 20c
+     23c 28c 30c ...'.
+
+     The material in each tab column (i.e., the column between two tab
+     stops) may be justified to the right or left or centered in the
+     column.  This is specified by appending `R', `L', or `C' to the tab
+     specifier.  The default justification is `L'.  Example:
+
+
+          .ta 1i 2iC 3iR
+
+     Some notes:
+
+        * The default unit of the `ta' request is `m'.
+
+        * A tab stop is converted into a non-breakable horizontal
+          movement which can be neither stretched nor squeezed.  For
+          example,
+
+
+               .ds foo a\tb\tc
+               .ta T 5i
+               \*[foo]
+
+          creates a single line which is a bit longer than 10 inches (a
+          string is used to show exactly where the tab characters are).
+          Now consider the following:
+
+
+               .ds bar a\tb b\tc
+               .ta T 5i
+               \*[bar]
+
+          `gtroff' first converts the tab stops of the line into
+          unbreakable horizontal movements, then splits the line after
+          the second `b' (assuming a sufficiently short line length).
+          Usually, this isn't what the user wants.
+
+        * Superfluous tabs (i.e., tab characters which do not
+          correspond to a tab stop) are ignored except the first one
+          which delimits the characters belonging to the last tab stop
+          for right-justifying or centering.  Consider the following
+          example
+
+
+               .ds Z   foo\tbar\tfoo
+               .ds ZZ  foo\tbar\tfoobar
+               .ds ZZZ foo\tbar\tfoo\tbar
+               .ta 2i 4iR
+               \*[Z]
+               .br
+               \*[ZZ]
+               .br
+               \*[ZZZ]
+               .br
+
+          which produces the following output:
+
+
+               foo                 bar              foo
+               foo                 bar           foobar
+               foo                 bar              foobar
+
+          The first line right-justifies the second `foo' relative to
+          the tab stop.  The second line right-justifies `foobar'.  The
+          third line finally right-justifies only `foo' because of the
+          additional tab character which marks the end of the string
+          belonging to the last defined tab stop.
+
+        * Tab stops are associated with the current environment (*note
+          Environments::).
+
+        * Calling `ta' without an argument removes all tab stops.
+
+        * The start-up value of `gtroff' is `T 0.8i'.
+
+     The read-only number register `.tabs' contains a string
+     representation of the current tab settings suitable for use as an
+     argument to the `ta' request.
+
+
+          .ds tab-string \n[.tabs]
+          \*[tab-string]
+              => T120u
+
+     The `troff' version of the Plan 9 operating system uses register
+     `.S' for the same purpose.
+
+ -- Request: .tc [fill-glyph]
+     Normally `gtroff' fills the space to the next tab stop with
+     whitespace.  This can be changed with the `tc' request.  With no
+     argument `gtroff' reverts to using whitespace, which is the
+     default.  The value of this "tab repetition character" is
+     associated with the current environment (*note Environments::).(1)
+     (*note Tabs and Fields-Footnote-1::)
+
+ -- Request: .linetabs n
+ -- Register: \n[.linetabs]
+     If N is missing or not zero, enable "line-tabs" mode, or disable
+     it otherwise (the default).  In line-tabs mode, `gtroff' computes
+     tab distances relative to the (current) output line instead of the
+     input line.
+
+     For example, the following code:
+
+
+          .ds x a\t\c
+          .ds y b\t\c
+          .ds z c
+          .ta 1i 3i
+          \*x
+          \*y
+          \*z
+
+     in normal mode, results in the output
+
+
+          a         b         c
+
+     in line-tabs mode, the same code outputs
+
+
+          a         b                   c
+
+     Line-tabs mode is associated with the current environment.  The
+     read-only register `.linetabs' is set to 1 if in line-tabs mode,
+     and 0 in normal mode.
+
+* Menu:
+
+* Leaders::
+* Fields::
+
+
+File: groff,  Node: Tabs and Fields-Footnotes,  Up: Tabs and Fields
+
+   (1) "Tab repetition character" is a misnomer since it is an output
+glyph.
+
+
+File: groff,  Node: Leaders,  Next: Fields,  Prev: Tabs and Fields,  Up: Tabs and Fields
+
+5.10.1 Leaders
+--------------
+
+Sometimes it may may be desirable to use the `tc' request to fill a
+particular tab stop with a given glyph (for example dots in a table of
+contents), but also normal tab stops on the rest of the line.  For this
+`gtroff' provides an alternate tab mechanism, called "leaders" which
+does just that.
+
+   A leader character (character code 1) behaves similarly to a tab
+character: It moves to the next tab stop.  The only difference is that
+for this movement, the fill glyph defaults to a period character and
+not to space.
+
+ -- Escape: \a
+     This escape is a non-interpreted leader character.  In copy mode
+     (*note Copy-in Mode::), `\a' is the same as a real leader
+     character.
+
+ -- Request: .lc [fill-glyph]
+     Declare the "leader repetition character".(1) (*note
+     Leaders-Footnote-1::) Without an argument, leaders act the same as
+     tabs (i.e., using whitespace for filling).  `gtroff''s start-up
+     value is a dot (`.').  The value of the leader repetition
+     character is associated with the current environment (*note
+     Environments::).
+
+   For a table of contents, to name an example, tab stops may be
+defined so that the section number is one tab stop, the title is the
+second with the remaining space being filled with a line of dots, and
+then the page number slightly separated from the dots.
+
+
+     .ds entry 1.1\tFoo\a\t12
+     .lc .
+     .ta 1i 5i +.25i
+     \*[entry]
+
+This produces
+
+
+     1.1  Foo..........................................  12
+
+
+File: groff,  Node: Leaders-Footnotes,  Up: Leaders
+
+   (1) "Leader repetition character" is a misnomer since it is an
+output glyph.
+
+
+File: groff,  Node: Fields,  Prev: Leaders,  Up: Tabs and Fields
+
+5.10.2 Fields
+-------------
+
+"Fields" are a more general way of laying out tabular data.  A field is
+defined as the data between a pair of "delimiting characters".  It
+contains substrings which are separated by "padding characters".  The
+width of a field is the distance on the _input_ line from the position
+where the field starts to the next tab stop.  A padding character
+inserts stretchable space similar to TeX's `\hss' command (thus it can
+even be negative) to make the sum of all substring lengths plus the
+stretchable space equal to the field width.  If more than one padding
+character is inserted, the available space is evenly distributed among
+them.
+
+ -- Request: .fc [delim-char [padding-char]]
+     Define a delimiting and a padding character for fields.  If the
+     latter is missing, the padding character defaults to a space
+     character.  If there is no argument at all, the field mechanism is
+     disabled (which is the default).  Note that contrary to e.g. the
+     tab repetition character, delimiting and padding characters are
+     _not_ associated to the current environment (*note Environments::).
+
+     Example:
+
+
+          .fc # ^
+          .ta T 3i
+          #foo^bar^smurf#
+          .br
+          #foo^^bar^smurf#
+
+     and here the result:
+
+
+          foo         bar          smurf
+          foo            bar       smurf
+
+
+
+File: groff,  Node: Character Translations,  Next: Troff and Nroff Mode,  Prev: Tabs and Fields,  Up: gtroff Reference
+
+5.11 Character Translations
+===========================
+
+The control character (`.') and the no-break control character (`'')
+can be changed with the `cc' and `c2' requests, respectively.
+
+ -- Request: .cc [c]
+     Set the control character to C.  With no argument the default
+     control character `.' is restored.  The value of the control
+     character is associated with the current environment (*note
+     Environments::).
+
+ -- Request: .c2 [c]
+     Set the no-break control character to C.  With no argument the
+     default control character `'' is restored.  The value of the
+     no-break control character is associated with the current
+     environment (*note Environments::).
+
+ -- Request: .eo
+     Disable the escape mechanism completely.  After executing this
+     request, the backslash character `\' no longer starts an escape
+     sequence.
+
+     This request can be very helpful in writing macros since it is not
+     necessary then to double the escape character.  Here an example:
+
+
+          .\" This is a simplified version of the
+          .\" .BR request from the man macro package
+          .eo
+          .de BR
+          .  ds result \&
+          .  while (\n[.$] >= 2) \{\
+          .    as result \fB\$1\fR\$2
+          .    shift 2
+          .  \}
+          .  if \n[.$] .as result \fB\$1
+          \*[result]
+          .  ft R
+          ..
+          .ec
+
+
+ -- Request: .ec [c]
+     Set the escape character to C.  With no argument the default
+     escape character `\' is restored.  It can be also used to
+     re-enable the escape mechanism after an `eo' request.
+
+     Note that changing the escape character globally will likely break
+     macro packages since `gtroff' has no mechanism to `intern' macros,
+     i.e., to convert a macro definition into an internal form which is
+     independent of its representation (TeX has this mechanism).  If a
+     macro is called, it is executed literally.
+
+ -- Request: .ecs
+ -- Request: .ecr
+     The `ecs' request saves the current escape character in an
+     internal register.  Use this request in combination with the `ec'
+     request to temporarily change the escape character.
+
+     The `ecr' request restores the escape character saved with `ecs'.
+     Without a previous call to `ecs', this request sets the escape
+     character to `\'.
+
+ -- Escape: \\
+ -- Escape: \e
+ -- Escape: \E
+     Print the current escape character (which is the backslash
+     character `\' by default).
+
+     `\\' is a `delayed' backslash; more precisely, it is the default
+     escape character followed by a backslash, which no longer has
+     special meaning due to the leading escape character.  It is _not_
+     an escape sequence in the usual sense!  In any unknown escape
+     sequence `\X' the escape character is ignored and X is printed.
+     But if X is equal to the current escape character, no warning is
+     emitted.
+
+     As a consequence, only at top-level or in a diversion a backslash
+     glyph is printed; in copy-in mode, it expands to a single
+     backslash which then combines with the following character to an
+     escape sequence.
+
+     The `\E' escape differs from `\e' by printing an escape character
+     that is not interpreted in copy mode.  Use this to define strings
+     with escapes that work when used in copy mode (for example, as a
+     macro argument).  The following example defines strings to begin
+     and end a superscript:
+
+
+          .ds { \v'-.3m'\s'\En[.s]*60/100'
+          .ds } \s0\v'.3m'
+
+     Another example to demonstrate the differences between the various
+     escape sequences, using a strange escape character, `-'.
+
+
+          .ec -
+          .de xxx
+          --A'123'
+          ..
+          .xxx
+              => -A'foo'
+
+     The result is surprising for most users, expecting `1' since `foo'
+     is a valid identifier.  What has happened?  As mentioned above,
+     the leading escape character makes the following character
+     ordinary.  Written with the default escape character the sequence
+     `--' becomes `\-' - this is the minus sign.
+
+     If the escape character followed by itself is a valid escape
+     sequence, only `\E' yields the expected result:
+
+
+          .ec -
+          .de xxx
+          -EA'123'
+          ..
+          .xxx
+              => 1
+
+
+ -- Escape: \.
+     Similar to `\\', the sequence `\.' isn't a real escape sequence.
+     As before, a warning message is suppressed if the escape character
+     is followed by a dot, and the dot itself is printed.
+
+
+          .de foo
+          .  nop foo
+          .
+          .  de bar
+          .    nop bar
+          \\..
+          .
+          ..
+          .foo
+          .bar
+              => foo bar
+
+     The first backslash is consumed while the macro is read, and the
+     second is swallowed while exexuting macro `foo'.
+
+   A "translation" is a mapping of an input character to an output
+glyph.  The mapping occurs at output time, i.e., the input character
+gets assigned the metric information of the mapped output character
+right before input tokens are converted to nodes (*note Gtroff
+Internals::, for more on this process).
+
+ -- Request: .tr abcd...
+ -- Request: .trin abcd...
+     Translate character A to glyph B, character C to glyph D, etc.  If
+     there is an odd number of arguments, the last one is translated to
+     an unstretchable space (`\ ').
+
+     The `trin' request is identical to `tr', but when you unformat a
+     diversion with `asciify' it ignores the translation.  *Note
+     Diversions::, for details about the `asciify' request.
+
+     Some notes:
+
+        * Special characters (`\(XX', `\[XXX]', `\C'XXX'', `\'', `\`',
+          `\-', `\_'), glyphs defined with the `char' request, and
+          numbered glyphs (`\N'XXX'') can be translated also.
+
+        * The `\e' escape can be translated also.
+
+        * Characters can be mapped onto the `\%' and `\~' escapes (but
+          `\%' and `\~' can't be mapped onto another glyph).
+
+        * The following characters can't be translated: space (with one
+          exception, see below), backspace, newline, leader (and `\a'),
+          tab (and `\t').
+
+        * Translations are not considered for finding the soft hyphen
+          character set with the `shc' request.
+
+        * The pair `C\&' (this is an arbitrary character C followed by
+          the zero width space character) maps this character to
+          nothing.
+
+
+               .tr a\&
+               foo bar
+                   => foo br
+
+          It is even possible to map the space character to nothing:
+
+
+               .tr aa \&
+               foo bar
+                   => foobar
+
+          As shown in the example, the space character can't be the
+          first character/glyph pair as an argument of `tr'.
+          Additionally, it is not possible to map the space character
+          to any other glyph; requests like `.tr aa x' undo `.tr aa \&'
+          instead.
+
+          If justification is active, lines are justified in spite of
+          the `empty' space character (but there is no minimal
+          distance, i.e. the space character, between words).
+
+        * After an output glyph has been constructed (this happens at
+          the moment immediately before the glyph is appended to an
+          output glyph list, either by direct output, in a macro,
+          diversion, or string), it is no longer affected by `tr'.
+
+        * Translating character to glyphs where one of them or both are
+          undefined is possible also; `tr' does not check whether the
+          entities in its argument do exist.
+
+          *Note Gtroff Internals::.
+
+        * `troff' no longer has a hard-coded dependency on Latin-1; all
+          `charXXX' entities have been removed from the font
+          description files.  This has a notable consequence which
+          shows up in warnings like `can't find character with input
+          code XXX' if the `tr' request isn't handled properly.
+
+          Consider the following translation:
+
+
+               .tr éÉ
+
+          This maps input character `é' onto glyph `É', which is
+          identical to glyph `char201'.  But this glyph intentionally
+          doesn't exist!  Instead, `\[char201]' is treated as an input
+          character entity and is by default mapped onto `\['E]', and
+          `gtroff' doesn't handle translations of translations.
+
+          The right way to write the above translation is
+
+
+               .tr é\['E]
+
+          With other words, the first argument of `tr' should be an
+          input character or entity, and the second one a glyph entity.
+
+        * Without an argument, the `tr' request is ignored.
+
+ -- Request: .trnt abcd...
+     `trnt' is the same as the `tr' request except that the
+     translations do not apply to text that is transparently throughput
+     into a diversion with `\!'.  *Note Diversions::, for more
+     information.
+
+     For example,
+
+
+          .tr ab
+          .di x
+          \!.tm a
+          .di
+          .x
+
+     prints `b' to the standard error stream; if `trnt' is used instead
+     of `tr' it prints `a'.
+
+
+File: groff,  Node: Troff and Nroff Mode,  Next: Line Layout,  Prev: Character Translations,  Up: gtroff Reference
+
+5.12 Troff and Nroff Mode
+=========================
+
+Originally, `nroff' and `troff' were two separate programs, the former
+for TTY output, the latter for everything else.  With GNU `troff', both
+programs are merged into one executable, sending its output to a device
+driver (`grotty' for TTY devices, `grops' for POSTSCRIPT, etc.) which
+interprets the intermediate output of `gtroff'.  For UNIX `troff' it
+makes sense to talk about "Nroff mode" and "Troff mode" since the
+differences are hardcoded.  For GNU `troff', this distinction is not
+appropriate because `gtroff' simply takes the information given in the
+font files for a particular device without handling requests specially
+if a TTY output device is used.
+
+   Usually, a macro package can be used with all output devices.
+Nevertheless, it is sometimes necessary to make a distinction between
+TTY and non-TTY devices: `gtroff' provides two built-in conditions `n'
+and `t' for the `if', `ie', and `while' requests to decide whether
+`gtroff' shall behave like `nroff' or like `troff'.
+
+ -- Request: .troff
+     Make the `t' built-in condition true (and the `n' built-in
+     condition false) for `if', `ie', and `while' conditional requests.
+     This is the default if `gtroff' (_not_ `groff') is started with
+     the `-R' switch to avoid loading of the start-up files `troffrc'
+     and `troffrc-end'.  Without `-R', `gtroff' stays in troff mode if
+     the output device is not a TTY (e.g. `ps').
+
+ -- Request: .nroff
+     Make the `n' built-in condition true (and the `t' built-in
+     condition false) for `if', `ie', and `while' conditional requests.
+     This is the default if `gtroff' uses a TTY output device; the
+     code for switching to nroff mode is in the file `tty.tmac' which
+     is loaded by the start-up file `troffrc'.
+
+   *Note Conditionals and Loops::, for more details on built-in
+conditions.
+
+
+File: groff,  Node: Line Layout,  Next: Line Control,  Prev: Troff and Nroff Mode,  Up: gtroff Reference
+
+5.13 Line Layout
+================
+
+The following drawing shows the dimensions which `gtroff' uses for
+placing a line of output onto the page.  They are labeled with the
+request which manipulates each dimension.
+
+
+                     -->| in |<--
+                        |<-----------ll------------>|
+                   +----+----+----------------------+----+
+                   |    :    :                      :    |
+                   +----+----+----------------------+----+
+                -->| po |<--
+                   |<--------paper width---------------->|
+
+These dimensions are:
+
+`po'
+     "Page offset" - this is the leftmost position of text on the final
+     output, defining the "left margin".
+
+`in'
+     "Indentation" - this is the distance from the left margin where
+     text is printed.
+
+`ll'
+     "Line length" - this is the distance from the left margin to right
+     margin.
+
+   A simple demonstration:
+
+
+     .ll 3i
+     This is text without indentation.
+     The line length has been set to 3\~inch.
+     .in +.5i
+     .ll -.5i
+     Now the left and right margins are both increased.
+     .in
+     .ll
+     Calling .in and .ll without parameters restore
+     the previous values.
+
+   Result:
+
+
+     This  is text without indenta-
+     tion.   The  line  length  has
+     been set to 3 inch.
+          Now   the  left  and
+          right  margins   are
+          both increased.
+     Calling  .in  and  .ll without
+     parameters restore the  previ-
+     ous values.
+
+ -- Request: .po [offset]
+ -- Request: .po +offset
+ -- Request: .po -offset
+ -- Register: \n[.o]
+     Set horizontal page offset to OFFSET (or increment or decrement
+     the current value by OFFSET).  Note that this request does not
+     cause a break, so changing the page offset in the middle of text
+     being filled may not yield the expected result.  The initial value
+     is 1i.  For TTY output devices, it is set to 0 in the startup file
+     `troffrc'; the default scaling indicator is `m' (and not `v' as
+     incorrectly documented in the original UNIX troff manual).
+
+     The current page offset can be found in the read-only number
+     register `.o'.
+
+     If `po' is called without an argument, the page offset is reset to
+     the previous value before the last call to `po'.
+
+
+          .po 3i
+          \n[.o]
+              => 720
+          .po -1i
+          \n[.o]
+              => 480
+          .po
+          \n[.o]
+              => 720
+
+
+ -- Request: .in [indent]
+ -- Request: .in +indent
+ -- Request: .in -indent
+ -- Register: \n[.i]
+     Set indentation to INDENT (or increment or decrement the current
+     value by INDENT).  This request causes a break.  Initially, there
+     is no indentation.
+
+     If `in' is called without an argument, the indentation is reset to
+     the previous value before the last call to `in'.  The default
+     scaling indicator is `m'.
+
+     The indentation is associated with the current environment (*note
+     Environments::).
+
+     If a negative indentation value is specified (which is not
+     allowed), `gtroff' emits a warning of type `range' and sets the
+     indentation to zero.
+
+     The effect of `in' is delayed until a partially collected line (if
+     it exists) is output.  A temporary indentation value is reset to
+     zero also.
+
+     The current indentation (as set by `in') can be found in the
+     read-only number register `.i'.
+
+ -- Request: .ti offset
+ -- Request: .ti +offset
+ -- Request: .ti -offset
+ -- Register: \n[.in]
+     Temporarily indent the next output line by OFFSET.  If an
+     increment or decrement value is specified, adjust the temporary
+     indentation relative to the value set by the `in' request.
+
+     This request causes a break; its value is associated with the
+     current environment (*note Environments::).  The default scaling
+     indicator is `m'.  A call of `ti' without an argument is ignored.
+
+     If the total indentation value is negative (which is not allowed),
+     `gtroff' emits a warning of type `range' and sets the temporary
+     indentation to zero.  `Total indentation' is either OFFSET if
+     specified as an absolute value, or the temporary plus normal
+     indentation, if OFFSET is given as a relative value.
+
+     The effect of `ti' is delayed until a partially collected line (if
+     it exists) is output.
+
+     The read-only number register `.in' is the indentation that applies
+     to the current output line.
+
+     The difference between `.i' and `.in' is that the latter takes
+     into account whether a partially collected line still uses the old
+     indentation value or a temporary indentation value is active.
+
+ -- Request: .ll [length]
+ -- Request: .ll +length
+ -- Request: .ll -length
+ -- Register: \n[.l]
+ -- Register: \n[.ll]
+     Set the line length to LENGTH (or increment or decrement the
+     current value by LENGTH).  Initially, the line length is set to
+     6.5i.  The effect of `ll' is delayed until a partially collected
+     line (if it exists) is output.  The default scaling indicator is
+     `m'.
+
+     If `ll' is called without an argument, the line length is reset to
+     the previous value before the last call to `ll'.  If a negative
+     line length is specified (which is not allowed), `gtroff' emits a
+     warning of type `range' and sets the line length to zero.
+
+     The line length is associated with the current environment (*note
+     Environments::).
+
+     The current line length (as set by `ll') can be found in the
+     read-only number register `.l'.  The read-only number register
+     `.ll' is the line length that applies to the current output line.
+
+     Similar to `.i' and `.in', the difference between `.l' and `.ll'
+     is that the latter takes into account whether a partially
+     collected line still uses the old line length value.
+
+
+File: groff,  Node: Line Control,  Next: Page Layout,  Prev: Line Layout,  Up: gtroff Reference
+
+5.14 Line Control
+=================
+
+It is important to understand how `gtroff' handles input and output
+lines.
+
+   Many escapes use positioning relative to the input line.  For
+example, this
+
+
+     This is a \h'|1.2i'test.
+
+     This is a
+     \h'|1.2i'test.
+
+produces
+
+
+     This is a   test.
+
+     This is a             test.
+
+   The main usage of this feature is to define macros which act exactly
+at the place where called.
+
+
+     .\" A simple macro to underline a word
+     .de underline
+     .  nop \\$1\l'|0\[ul]'
+     ..
+
+In the above example, `|0' specifies a negative distance from the
+current position (at the end of the just emitted argument `\$1') back
+to the beginning of the input line.  Thus, the `\l' escape draws a line
+from right to left.
+
+   `gtroff' makes a difference between input and output line
+continuation; the latter is also called "interrupting" a line.
+
+ -- Escape: \<RET>
+ -- Escape: \c
+ -- Register: \n[.int]
+     Continue a line.  `\<RET>' (this is a backslash at the end of a
+     line immediately followed by a newline) works on the input level,
+     suppressing the effects of the following newline in the input.
+
+
+          This is a \
+          .test
+              => This is a .test
+
+     The `|' operator is also affected.
+
+     `\c' works on the output level.  Anything after this escape on the
+     same line is ignored, except `\R' which works as usual.  Anything
+     before `\c' on the same line will be appended to the current
+     partial output line.  The next non-command line after an
+     interrupted line counts as a new input line.
+
+     The visual results depend on whether no-fill mode is active.
+
+        * If no-fill mode is active (using the `nf' request), the next
+          input text line after `\c' will be handled as a continuation
+          of the same input text line.
+
+
+               .nf
+               This is a \c
+               test.
+                   => This is a test.
+
+        * If fill mode is active (using the `fi' request), a word
+          interrupted with `\c' will be continued with the text on the
+          next input text line, without an intervening space.
+
+
+               This is a te\c
+               st.
+                   => This is a test.
+
+
+     Note that an intervening control line which causes a break is
+     stronger than `\c', flushing out the current partial line in the
+     usual way.
+
+     The `.int' register contains a positive value if the last output
+     line was interrupted with `\c'; this is associated with the
+     current environment (*note Environments::).
+
+
+File: groff,  Node: Page Layout,  Next: Page Control,  Prev: Line Control,  Up: gtroff Reference
+
+5.15 Page Layout
+================
+
+`gtroff' provides some very primitive operations for controlling page
+layout.
+
+ -- Request: .pl [length]
+ -- Request: .pl +length
+ -- Request: .pl -length
+ -- Register: \n[.p]
+     Set the "page length" to LENGTH (or increment or decrement the
+     current value by LENGTH).  This is the length of the physical
+     output page.  The default scaling indicator is `v'.
+
+     The current setting can be found in the read-only number register
+     `.p'.
+
+     Note that this only specifies the size of the page, not the top and
+     bottom margins.  Those are not set by `gtroff' directly.  *Note
+     Traps::, for further information on how to do this.
+
+     Negative `pl' values are possible also, but not very useful: No
+     trap is sprung, and each line is output on a single page (thus
+     suppressing all vertical spacing).
+
+     If no argument or an invalid argument is given, `pl' sets the page
+     length to 11i.
+
+   `gtroff' provides several operations which help in setting up top
+and bottom titles (or headers and footers).
+
+ -- Request: .tl 'left'center'right'
+     Print a "title line".  It consists of three parts: a left
+     justified portion, a centered portion, and a right justified
+     portion.  The argument separator `'' can be replaced with any
+     character not occurring in the title line.  The `%' character is
+     replaced with the current page number.  This character can be
+     changed with the `pc' request (see below).
+
+     Without argument, `tl' is ignored.
+
+     Some notes:
+
+        * A title line is not restricted to the top or bottom of a page.
+
+        * `tl' prints the title line immediately, ignoring a partially
+          filled line (which stays untouched).
+
+        * It is not an error to omit closing delimiters.  For example,
+          `.tl /foo' is equivalent to `.tl /foo///': It prints a title
+          line with the left justified word `foo'; the centered and
+          right justfied parts are empty.
+
+        * `tl' accepts the same parameter delimiting characters as the
+          `\A' escape; see *Note Escapes::.
+
+ -- Request: .lt [length]
+ -- Request: .lt +length
+ -- Request: .lt -length
+ -- Register: \n[.lt]
+     The title line is printed using its own line length, which is
+     specified (or incremented or decremented) with the `lt' request.
+     Initially, the title line length is set to 6.5i.  If a negative
+     line length is specified (which is not allowed), `gtroff' emits a
+     warning of type `range' and sets the title line length to zero.
+     The default scaling indicator is `m'.  If `lt' is called without
+     an argument, the title length is reset to the previous value
+     before the last call to `lt'.
+
+     The current setting of this is available in the `.lt' read-only
+     number register; it is associated with the current environment
+     (*note Environments::).
+
+ -- Request: .pn page
+ -- Request: .pn +page
+ -- Request: .pn -page
+ -- Register: \n[.pn]
+     Change (increase or decrease) the page number of the _next_ page.
+     The only argument is the page number; the request is ignored
+     without a parameter.
+
+     The read-only number register `.pn' contains the number of the next
+     page: either the value set by a `pn' request, or the number of the
+     current page plus 1.
+
+ -- Request: .pc [char]
+     Change the page number character (used by the `tl' request) to a
+     different character.  With no argument, this mechanism is disabled.
+     Note that this doesn't affect the number register `%'.
+
+   *Note Traps::.
+
+
+File: groff,  Node: Page Control,  Next: Fonts and Symbols,  Prev: Page Layout,  Up: gtroff Reference
+
+5.16 Page Control
+=================
+
+ -- Request: .bp [page]
+ -- Request: .bp +page
+ -- Request: .bp -page
+ -- Register: \n[%]
+     Stop processing the current page and move to the next page.  This
+     request causes a break.  It can also take an argument to set
+     (increase, decrease) the page number of the next page (which
+     actually becomes the current page after `bp' has finished).  The
+     difference between `bp' and `pn' is that `pn' does not cause a
+     break or actually eject a page.  *Note Page Layout::.
+
+
+          .de newpage                         \" define macro
+          'bp                                 \" begin page
+          'sp .5i                             \" vertical space
+          .tl 'left top'center top'right top' \" title
+          'sp .3i                             \" vertical space
+          ..                                  \" end macro
+
+     `bp' has no effect if not called within the top-level diversion
+     (*note Diversions::).
+
+     The read-write register `%' holds the current page number.
+
+     The number register `.pe' is set to 1 while `bp' is active.  *Note
+     Page Location Traps::.
+
+ -- Request: .ne [space]
+     It is often necessary to force a certain amount of space before a
+     new page occurs.  This is most useful to make sure that there is
+     not a single "orphan" line left at the bottom of a page.  The `ne'
+     request ensures that there is a certain distance, specified by the
+     first argument, before the next page is triggered (see *Note
+     Traps::, for further information).  The default scaling indicator
+     for `ne' is `v'; the default value of SPACE is 1v if no argument
+     is given.
+
+     For example, to make sure that no fewer than 2 lines get orphaned,
+     do the following before each paragraph:
+
+
+          .ne 2
+          text text text
+
+     `ne' will then automatically cause a page break if there is space
+     for one line only.
+
+ -- Request: .sv [space]
+ -- Request: .os
+     `sv' is similar to the `ne' request; it reserves the specified
+     amount of vertical space.  If the desired amount of space exists
+     before the next trap (or the bottom page boundary if no trap is
+     set), the space is output immediately (ignoring a partially filled
+     line which stays untouched).  If there is not enough space, it is
+     stored for later output via the `os' request.  The default value
+     is 1v if no argument is given; the default scaling indicator is
+     `v'.
+
+     Both `sv' and `os' ignore no-space mode.  While the `sv' request
+     allows negative values for SPACE, `os' will ignore them.
+
+ -- Register: \n[nl]
+     This register contains the current vertical position.  If the
+     vertical position is zero and the top of page transition hasn't
+     happened yet, `nl' is set to negative value.  `gtroff' itself does
+     this at the very beginning of a document before anything has been
+     printed, but the main usage is to plant a header trap on a page if
+     this page has already started.
+
+     Consider the following:
+
+
+          .de xxx
+          .  sp
+          .  tl ''Header''
+          .  sp
+          ..
+          .
+          First page.
+          .bp
+          .wh 0 xxx
+          .nr nl (-1)
+          Second page.
+
+     Result:
+
+
+          First page.
+
+          ...
+
+                                       Header
+
+          Second page.
+
+          ...
+
+     Without resetting `nl' to a negative value, the just planted trap
+     would be active beginning with the _next_ page, not the current
+     one.
+
+     *Note Diversions::, for a comparison with the `.h' and `.d'
+     registers.
+
+
+File: groff,  Node: Fonts and Symbols,  Next: Sizes,  Prev: Page Control,  Up: gtroff Reference
+
+5.17 Fonts and Symbols
+======================
+
+`gtroff' can switch fonts at any point in the text.
+
+   The basic set of fonts is `R', `I', `B', and `BI'.  These are Times
+Roman, Italic, Bold, and Bold Italic.  For non-TTY devices, there is
+also at least one symbol font which contains various special symbols
+(Greek, mathematics).
+
+* Menu:
+
+* Changing Fonts::
+* Font Families::
+* Font Positions::
+* Using Symbols::
+* Special Fonts::
+* Artificial Fonts::
+* Ligatures and Kerning::
+
+
+File: groff,  Node: Changing Fonts,  Next: Font Families,  Prev: Fonts and Symbols,  Up: Fonts and Symbols
+
+5.17.1 Changing Fonts
+---------------------
+
+ -- Request: .ft [font]
+ -- Escape: \ff
+ -- Escape: \f(fn
+ -- Escape: \f[font]
+ -- Register: \n[.sty]
+     The `ft' request and the `\f' escape change the current font to
+     FONT (one-character name F, two-character name FN).
+
+     If FONT is a style name (as set with the `sty' request or with the
+     `styles' command in the `DESC' file), use it within the current
+     font family (as set with the `fam' request, `\F' escape, or with
+     the `family' command in the `DESC' file).
+
+     With no argument or using `P' as an argument, `.ft' switches to
+     the previous font.  Use `\f[]' to do this with the escape.  The
+     old syntax forms `\fP' or `\f[P]' are also supported.
+
+     Fonts are generally specified as upper-case strings, which are
+     usually 1 to 4 characters representing an abbreviation or acronym
+     of the font name.  This is no limitation, just a convention.
+
+     The example below produces two identical lines.
+
+
+          eggs, bacon,
+          .ft B
+          spam
+          .ft
+          and sausage.
+
+          eggs, bacon, \fBspam\fP and sausage.
+
+     Note that `\f' doesn't produce an input token in `gtroff'.  As a
+     consequence, it can be used in requests like `mc' (which expects a
+     single character as an argument) to change the font on the fly:
+
+
+          .mc \f[I]x\f[]
+
+     The current style name is available in the read-only number
+     register `.sty' (this is a string-valued register); if the current
+     font isn't a style, the empty string is returned.  It is
+     associated with the current environment.
+
+     *Note Font Positions::, for an alternative syntax.
+
+ -- Request: .ftr f [g]
+     Translate font F to font G.  Whenever a font named F is referred
+     to in a `\f' escape sequence, in the `F' and `S' conditional
+     operators, or in the `ft', `ul', `bd', `cs', `tkf', `special',
+     `fspecial', `fp', or `sty' requests, font G is used.  If G is
+     missing or equal to F the translation is undone.
+
+
+File: groff,  Node: Font Families,  Next: Font Positions,  Prev: Changing Fonts,  Up: Fonts and Symbols
+
+5.17.2 Font Families
+--------------------
+
+Due to the variety of fonts available, `gtroff' has added the concept
+of "font families" and "font styles".  The fonts are specified as the
+concatenation of the font family and style.  Specifying a font without
+the family part causes `gtroff' to use that style of the current family.
+
+   Currently, fonts for the devices `-Tps', `-Tdvi', `-Tlj4', `-Tlbp',
+and the X11 fonts are set up to this mechanism.  By default, `gtroff'
+uses the Times family with the four styles `R', `I', `B', and `BI'.
+
+   This way, it is possible to use the basic four fonts and to select a
+different font family on the command line (*note Groff Options::).
+
+ -- Request: .fam [family]
+ -- Register: \n[.fam]
+ -- Escape: \Ff
+ -- Escape: \F(fm
+ -- Escape: \F[family]
+ -- Register: \n[.fn]
+     Switch font family to FAMILY (one-character name F, two-character
+     name FM).  If no argument is given, switch back to the previous
+     font family.  Use `\F[]' to do this with the escape.  Note that
+     `\FP' doesn't work; it selects font family `P' instead.
+
+     The value at start-up is `T'.  The current font family is
+     available in the read-only number register `.fam' (this is a
+     string-valued register); it is associated with the current
+     environment.
+
+
+          spam,
+          .fam H    \" helvetica family
+          spam,     \" used font is family H + style R = HR
+          .ft B     \" family H + style B = font HB
+          spam,
+          .fam T    \" times family
+          spam,     \" used font is family T + style B = TB
+          .ft AR    \" font AR (not a style)
+          baked beans,
+          .ft R     \" family T + style R = font TR
+          and spam.
+
+     Note that `\F' doesn't produce an input token in `gtroff'.  As a
+     consequence, it can be used in requests like `mc' (which expects a
+     single character as an argument) to change the font family on the
+     fly:
+
+
+          .mc \F[P]x\F[]
+
+     The `.fn' register contains the current "real font name" of the
+     current font.  This is a string-valued register.  If the current
+     font is a style, the value of `\n[.fn]' is the proper
+     concatenation of family and style name.
+
+ -- Request: .sty n style
+     Associate STYLE with font position N.  A font position can be
+     associated either with a font or with a style.  The current font
+     is the index of a font position and so is also either a font or a
+     style.  If it is a style, the font that is actually used is the
+     font which name is the concatenation of the name of the current
+     family and the name of the current style.  For example, if the
+     current font is 1 and font position 1 is associated with style `R'
+     and the current font family is `T', then font `TR' will be used.
+     If the current font is not a style, then the current family is
+     ignored.  If the requests `cs', `bd', `tkf', `uf', or `fspecial'
+     are applied to a style, they will instead be applied to the member
+     of the current family corresponding to that style.
+
+     N must be a non-negative integer value.
+
+     The default family can be set with the `-f' option (*note Groff
+     Options::).  The `styles' command in the `DESC' file controls
+     which font positions (if any) are initially associated with styles
+     rather than fonts.  For example, the default setting for
+     POSTSCRIPT fonts
+
+
+          styles R I B BI
+
+     is equivalent to
+
+
+          .sty 1 R
+          .sty 2 I
+          .sty 3 B
+          .sty 4 BI
+
+     `fam' and `\F' always check whether the current font position is
+     valid; this can give surprising results if the current font
+     position is associated with a style.
+
+     In the following example, we want to access the POSTSCRIPT font
+     `FooBar' from the font family `Foo':
+
+
+          .sty \n[.fp] Bar
+          .fam Foo
+              => warning: can't find font `FooR'
+
+     The default font position at start-up is 1; for the POSTSCRIPT
+     device, this is associated with style `R', so `gtroff' tries to
+     open `FooR'.
+
+     A solution to this problem is to use a dummy font like the
+     following:
+
+
+          .fp 0 dummy TR    \" set up dummy font at position 0
+          .sty \n[.fp] Bar  \" register style `Bar'
+          .ft 0             \" switch to font at position 0
+          .fam Foo          \" activate family `Foo'
+          .ft Bar           \" switch to font `FooBar'
+
+     *Note Font Positions::.
+
+
+File: groff,  Node: Font Positions,  Next: Using Symbols,  Prev: Font Families,  Up: Fonts and Symbols
+
+5.17.3 Font Positions
+---------------------
+
+For the sake of old phototypesetters and compatibility with old versions
+of `troff', `gtroff' has the concept of font "positions", on which
+various fonts are mounted.
+
+ -- Request: .fp pos font [external-name]
+ -- Register: \n[.f]
+ -- Register: \n[.fp]
+     Mount font FONT at position POS (which must be a non-negative
+     integer).  This numeric position can then be referred to with font
+     changing commands.  When `gtroff' starts it is using font
+     position 1 (which must exist; position 0 is unused usually at
+     start-up).
+
+     The current font in use, as a font position, is available in the
+     read-only number register `.f'.  This can be useful to remember the
+     current font for later recall.  It is associated with the current
+     environment (*note Environments::).
+
+
+          .nr save-font \n[.f]
+          .ft B
+          ... text text text ...
+          .ft \n[save-font]
+
+     The number of the next free font position is available in the
+     read-only number register `.fp'.  This is useful when mounting a
+     new font, like so:
+
+
+          .fp \n[.fp] NEATOFONT
+
+     Fonts not listed in the `DESC' file are automatically mounted on
+     the next available font position when they are referenced.  If a
+     font is to be mounted explicitly with the `fp' request on an unused
+     font position, it should be mounted on the first unused font
+     position, which can be found in the `.fp' register.  Although
+     `gtroff' does not enforce this strictly, it is not allowed to
+     mount a font at a position whose number is much greater (approx.
+     1000 positions) than that of any currently used position.
+
+     The `fp' request has an optional third argument.  This argument
+     gives the external name of the font, which is used for finding the
+     font description file.  The second argument gives the internal
+     name of the font which is used to refer to the font in `gtroff'
+     after it has been mounted.  If there is no third argument then the
+     internal name is used as the external name.  This feature makes it
+     possible to use fonts with long names in compatibility mode.
+
+   Both the `ft' request and the `\f' escape have alternative syntax
+forms to access font positions.
+
+ -- Request: .ft nnn
+ -- Escape: \fn
+ -- Escape: \f(nn
+ -- Escape: \f[nnn]
+     Change the current font position to NNN (one-digit position N,
+     two-digit position NN), which must be a non-negative integer.
+
+     If NNN is associated with a style (as set with the `sty' request
+     or with the `styles' command in the `DESC' file), use it within
+     the current font family (as set with the `fam' request, the `\F'
+     escape, or with the `family' command in the `DESC' file).
+
+
+          this is font 1
+          .ft 2
+          this is font 2
+          .ft                   \" switch back to font 1
+          .ft 3
+          this is font 3
+          .ft
+          this is font 1 again
+
+     *Note Changing Fonts::, for the standard syntax form.
+
+
+File: groff,  Node: Using Symbols,  Next: Special Fonts,  Prev: Font Positions,  Up: Fonts and Symbols
+
+5.17.4 Using Symbols
+--------------------
+
+A "glyph" is a graphical representation of a "character".  While a
+character is an abstract entity containing semantic information, a
+glyph is something which can be actually seen on screen or paper.  It
+is possible that a character has multiple glyph representation forms
+(for example, the character `A' can be either written in a roman or an
+italic font, yielding two different glyphs); sometimes more than one
+character maps to a single glyph (this is a "ligature" - the most
+common is `fi').
+
+   A "symbol" is simply a named glyph.  Within `gtroff', all glyph
+names of a particular font are defined in its font file.  If the user
+requests a glyph not available in this font, `gtroff' looks up an
+ordered list of "special fonts".  By default, the POSTSCRIPT output
+device supports the two special fonts `SS' (slanted symbols) and `S'
+(symbols) (the former is looked up before the latter).  Other output
+devices use different names for special fonts.  Fonts mounted with the
+`fonts' keyword in the `DESC' file are globally available.  To install
+additional special fonts locally (i.e. for a particular font), use the
+`fspecial' request.
+
+   Here the exact rules how `gtroff' searches a given symbol:
+
+   * If the symbol has been defined with the `char' request, use it.
+     This hides a symbol with the same name in the current font.
+
+   * Check the current font.
+
+   * If the symbol has been defined with the `fchar' request, use it.
+
+   * Check whether the current font has a font-specific list of special
+     fonts; test all fonts in the order of appearance in the last
+     `fspecial' call if appropriate.
+
+   * If the symbol has been defined with the `fschar' request for the
+     current font, use it.
+
+   * Check all fonts in the order of appearance in the last `special'
+     call.
+
+   * If the symbol has been defined with the `schar' request, use it.
+
+   * As a last resort, consult all fonts loaded up to now for special
+     fonts and check them, starting with the lowest font number.  Note
+     that this can sometimes lead to surprising results since the
+     `fonts' line in the `DESC' file often contains empty positions
+     which are filled later on.  For example, consider the following:
+
+
+          fonts 3 0 0 FOO
+
+     This mounts font `foo' at font position 3.  We assume that `FOO'
+     is a special font, containing glyph `foo', and that no font has
+     been loaded yet.  The line
+
+
+          .fspecial BAR BAZ
+
+     makes font `BAZ' special only if font `BAR' is active.  We further
+     assume that `BAZ' is really a special font, i.e., the font
+     description file contains the `special' keyword, and that it also
+     contains glyph `foo' with a special shape fitting to font `BAR'.
+     After executing `fspecial', font `BAR' is loaded at font
+     position 1, and `BAZ' at position 2.
+
+     We now switch to a new font `XXX', trying to access glyph `foo'
+     which is assumed to be missing.  There are neither font-specific
+     special fonts for `XXX' nor any other fonts made special with the
+     `special' request, so `gtroff' starts the search for special fonts
+     in the list of already mounted fonts, with increasing font
+     positions.  Consequently, it finds `BAZ' before `FOO' even for
+     `XXX' which is not the intended behaviour.
+
+   *Note Font Files::, and *Note Special Fonts::, for more details.
+
+   The list of available symbols is device dependent; see the
+`groff_char(7)' man page for a complete list of all glyphs.  For
+example, say
+
+
+     man -Tdvi groff_char > groff_char.dvi
+
+for a list using the default DVI fonts (not all versions of the `man'
+program support the `-T' option).  If you want to use an additional
+macro package to change the used fonts, `groff' must be called directly:
+
+
+     groff -Tdvi -mec -man groff_char.7 > groff_char.dvi
+
+   Glyph names not listed in groff_char(7) are derived algorithmically,
+using a simplified version of the Adobe Glyph List (AGL) algorithm
+which is described in
+`http://partners.adobe.com/asn/tech/type/unicodegn.jsp'.  The (frozen)
+set of glyph names which can't be derived algorithmically is called
+"groff glyph list (GGL)".
+
+   * A glyph for Unicode character U+XXXX[X[X]] which is not a
+     composite character will be named `uXXXX[X[X]]'.  X must be an
+     uppercase hexadecimal digit.  Examples: `u1234', `u008E',
+     `u12DB8'.  The largest Unicode value is 0x10FFFF.  There must be at
+     least four `X' digits; if necessary, add leading zeroes (after the
+     `u').  No zero padding is allowed for character codes greater than
+     0xFFFF.  Surrogates (i.e., Unicode values greater than 0xFFFF
+     represented with character codes from the surrogate area
+     U+D800-U+DFFF) are not allowed too.
+
+   * A glyph representing more than a single input character will be
+     named
+
+          `u' COMPONENT1 `_' COMPONENT2 `_' COMPONENT3 ...
+
+     Example: `u0045_0302_0301'.
+
+     For simplicity, all Unicode characters which are composites must be
+     decomposed maximally (this is normalization form D in the Unicode
+     standard); for example, `u00CA_0301' is not a valid glyph name
+     since U+00CA (LATIN CAPITAL LETTER E WITH CIRCUMFLEX) can be
+     further decomposed into U+0045 (LATIN CAPITAL LETTER E) and U+0302
+     (COMBINING CIRCUMFLEX ACCENT).  `u0045_0302_0301' is thus the
+     glyph name for U+1EBE, LATIN CAPITAL LETTER E WITH CIRCUMFLEX AND
+     ACUTE.
+
+   * groff maintains a table to decompose all algorithmically derived
+     glyph names which are composites itself.  For example, `u0100'
+     (LATIN LETTER A WITH MACRON) will be automatically decomposed into
+     `u0041_0304'.  Additionally, a glyph name of the GGL is preferred
+     to an algorithmically derived glyph name; groff also automatically
+     does the mapping.  Example: The glyph `u0045_0302' will be mapped
+     to `^E'.
+
+   * glyph names of the GGL can't be used in composite glyph names; for
+     example, `^E_u0301' is invalid.
+
+ -- Escape: \(nm
+ -- Escape: \[name]
+ -- Escape: \[component1 component2 ...]
+     Insert a symbol NAME (two-character name NM) or a composite glyph
+     with component glyphs COMPONENT1, COMPONENT2, .... There is no
+     special syntax for one-character names - the natural form `\N'
+     would collide with escapes.(1) (*note Using Symbols-Footnote-1::)
+
+     If NAME is undefined, a warning of type `char' is generated, and
+     the escape is ignored.  *Note Debugging::, for information about
+     warnings.
+
+     groff resolves `\[...]' with more than a single component as
+     follows:
+
+        * Any component which is found in the GGL will be converted to
+          the `uXXXX' form.
+
+        * Any component `uXXXX' which is found in the list of
+          decomposable glyphs will be decomposed.
+
+        * The resulting elements are then concatenated with `_'
+          inbetween, dropping the leading `u' in all elements but the
+          first.
+
+     No check for the existence of any component (similar to `tr'
+     request) will be done.
+
+     Examples:
+
+    `\[A ho]'
+          `A' maps to `u0041', `ho' maps to `u02DB', thus the final
+          glyph name would be `u0041_02DB'.  Note this is not the
+          expected result: The ogonek glyph `ho' is a spacing ogonek,
+          but for a proper composite a non-spacing ogonek (U+0328) is
+          necessary.  Looking into the file `composite.tmac' one can
+          find `.composite ho u0328' which changes the mapping of `ho'
+          while a composite glyph name is constructed, causing the
+          final glyph name to be `u0041_0328'.
+
+    `\[^E u0301]'
+    `\[^E aa]'
+    `\[E a^ aa]'
+    `\[E ^ ']'
+          `^E' maps to `u0045_0302', thus the final glyph name is
+          `u0045_0302_0301' in all forms (assuming proper calls of the
+          `composite' request).
+
+     It is not possible to define glyphs with names like `A ho' within
+     a groff font file.  This is not really a limitation; instead, you
+     have to define `u0041_0328'.
+
+ -- Escape: \C'xxx'
+     Typeset the glyph named XXX.(2) (*note Using Symbols-Footnote-2::)
+     Normally it is more convenient to use `\[XXX]', but `\C' has the
+     advantage that it is compatible with newer versions of AT&T
+     `troff' and is available in compatibility mode.
+
+ -- Request: .composite from to
+     Map glyph name FROM to glyph name TO if it is used in `\[...]'
+     with more than one component.  See above for examples.
+
+     This mapping is based on glyph names only; no check for the
+     existence of either glyph is done.
+
+     A set of default mappings for many accents can be found in the file
+     `composite.tmac' which is loaded at start-up.
+
+ -- Escape: \N'n'
+     Typeset the glyph with code N in the current font (`n' is *not*
+     the input character code).  The number N can be any non-negative
+     decimal integer.  Most devices only have glyphs with codes between
+     0 and 255; the Unicode output device uses codes in the range
+     0-65535.  If the current font does not contain a glyph with that
+     code, special fonts are _not_ searched.  The `\N' escape sequence
+     can be conveniently used in conjunction with the `char' request:
+
+
+          .char \[phone] \f[ZD]\N'37'
+
+     The code of each glyph is given in the fourth column in the font
+     description file after the `charset' command.  It is possible to
+     include unnamed glyphs in the font description file by using a
+     name of `---'; the `\N' escape sequence is the only way to use
+     these.
+
+     No kerning is applied to glyphs accessed with `\N'.
+
+   Some escape sequences directly map onto special glyphs.
+
+ -- Escape: \'
+     This is a backslash followed by the apostrophe character, ASCII
+     character `0x27' (EBCDIC character `0x7D').  The same as `\[aa]',
+     the acute accent.
+
+ -- Escape: \`
+     This is a backslash followed by ASCII character `0x60' (EBCDIC
+     character `0x79' usually).  The same as `\[ga]', the grave accent.
+
+ -- Escape: \-
+     This is the same as `\[-]', the minus sign in the current font.
+
+ -- Request: .cflags n c1 c2 ...
+     Input characters and symbols have certain properties associated
+     with it.(3) (*note Using Symbols-Footnote-3::)  These properties
+     can be modified with the `cflags' request.  The first argument is
+     the sum of the desired flags and the remaining arguments are the
+     characters or symbols to have those properties.  It is possible to
+     omit the spaces between the characters or symbols.
+
+    `1'
+          The character ends sentences (initially characters `.?!' have
+          this property).
+
+    `2'
+          Lines can be broken before the character (initially no
+          characters have this property).
+
+    `4'
+          Lines can be broken after the character (initially the
+          character `-' and the symbols `\[hy]' and `\[em]' have this
+          property).
+
+    `8'
+          The character overlaps horizontally if used as a horizontal
+          line building element.  Initially the symbols `\[ul]',
+          `\[rn]', `\[ru]', `\[radicalex]', and `\[sqrtex]' have this
+          property.
+
+    `16'
+          The character overlaps vertically if used as vertical line
+          building element.  Initially symbol `\[br]' has this property.
+
+    `32'
+          An end-of-sentence character followed by any number of
+          characters with this property is treated as the end of a
+          sentence if followed by a newline or two spaces; in other
+          words the character is "transparent" for the purposes of
+          end-of-sentence recognition - this is the same as having a
+          zero space factor in TeX (initially characters `"')]*' and
+          the symbols `\[dg]' and `\[rq]' have this property).
+
+ -- Request: .char g [string]
+ -- Request: .fchar g [string]
+ -- Request: .fschar f g [string]
+ -- Request: .schar g [string]
+     Define a new glyph G to be STRING (which can be empty).(4) (*note
+     Using Symbols-Footnote-4::)  Every time glyph G needs to be
+     printed, STRING is processed in a temporary environment and the
+     result is wrapped up into a single object.  Compatibility mode is
+     turned off and the escape character is set to `\' while STRING is
+     being processed.  Any emboldening, constant spacing or track
+     kerning is applied to this object rather than to individual
+     characters in STRING.
+
+     A glyph defined by these requests can be used just like a normal
+     glyph provided by the output device.  In particular, other
+     characters can be translated to it with the `tr' or `trin'
+     requests; it can be made the leader character by the `lc' request;
+     repeated patterns can be drawn with the glyph using the `\l' and
+     `\L' escape sequences; words containing the glyph can be
+     hyphenated correctly if the `hcode' request is used to give the
+     glyph's symbol a hyphenation code.
+
+     There is a special anti-recursion feature: Use of `g' within the
+     glyph's definition is handled like normal characters and symbols
+     not defined with `char'.
+
+     Note that the `tr' and `trin' requests take precedence if `char'
+     accesses the same symbol.
+
+
+          .tr XY
+          X
+              => Y
+          .char X Z
+          X
+              => Y
+          .tr XX
+          X
+              => Z
+
+     The `fchar' request defines a fallback glyph: `gtroff' only checks
+     for glyphs defined with `fchar' if it cannot find the glyph in the
+     current font.  `gtroff' carries out this test before checking
+     special fonts.
+
+     `fschar' defines a fallback glyph for font F: `gtroff' checks for
+     glyphs defined with `fschar' after the list of fonts declared as
+     font-specific special fonts with the `fspecial' request, but
+     before the list of fonts declared as global special fonts with the
+     `special' request.
+
+     Finally, the `schar' request defines a global fallback glyph:
+     `gtroff' checks for glyphs defined with `schar' after the list of
+     fonts declared as global special fonts with the `special' request,
+     but before the already mounted special fonts.
+
+     *Note Using Symbols::, for a detailed description of the glyph
+     searching mechanism in `gtroff'.
+
+ -- Request: .rchar c1 c2 ...
+ -- Request: .rfschar f c1 c2 ...
+     Remove the definitions of glyphs C1, C2, ....  This undoes the
+     effect of a `char', `fchar', or `schar' request.
+
+     It is possible to omit the whitespace between arguments.
+
+     The request `rfschar' removes glyph definitions defined with
+     `fschar' for glyph f.
+
+   *Note Special Characters::.
+
+
+File: groff,  Node: Using Symbols-Footnotes,  Up: Using Symbols
+
+   (1) Note that a one-character symbol is not the same as an input
+character, i.e., the character `a' is not the same as `\[a]'.  By
+default, `groff' defines only a single one-character symbol, `\[-]'; it
+is usually accessed as `\-'.  On the other hand, `gtroff' has the
+special feature that `\[charXXX]' is the same as the input character
+with character code XXX.  For example, `\[char97]' is identical to the
+letter `a' if ASCII encoding is active.
+
+   (2) `\C' is actually a misnomer since it accesses an output glyph.
+
+   (3) Note that the output glyphs themselves don't have such
+properties.  For `gtroff', a glyph is a numbered box with a given
+width, depth, and height, nothing else.  All manipulations with the
+`cflags' request work on the input level.
+
+   (4) `char' is a misnomer since an output glyph is defined.
+
+
+File: groff,  Node: Special Fonts,  Next: Artificial Fonts,  Prev: Using Symbols,  Up: Fonts and Symbols
+
+5.17.5 Special Fonts
+--------------------
+
+Special fonts are those that `gtroff' searches when it cannot find the
+requested glyph in the current font.  The Symbol font is usually a
+special font.
+
+   `gtroff' provides the following two requests to add more special
+fonts.  *Note Using Symbols::, for a detailed description of the glyph
+searching mechanism in `gtroff'.
+
+   Usually, only non-TTY devices have special fonts.
+
+ -- Request: .special [s1 s2 ...]
+ -- Request: .fspecial f [s1 s2 ...]
+     Use the `special' request to define special fonts.  Initially, this
+     list is empty.
+
+     Use the `fspecial' request to designate special fonts only when
+     font F is active.  Initially, this list is empty.
+
+     Previous calls to `special' or `fspecial' are overwritten; without
+     arguments, the particular list of special fonts is set to empty.
+     Special fonts are searched in the order they appear as arguments.
+
+     All fonts which appear in a call to `special' or `fspecial' are
+     loaded.
+
+     *Note Using Symbols::, for the exact search order of glyphs.
+
+
+File: groff,  Node: Artificial Fonts,  Next: Ligatures and Kerning,  Prev: Special Fonts,  Up: Fonts and Symbols
+
+5.17.6 Artificial Fonts
+-----------------------
+
+There are a number of requests and escapes for artificially creating
+fonts.  These are largely vestiges of the days when output devices did
+not have a wide variety of fonts, and when `nroff' and `troff' were
+separate programs.  Most of them are no longer necessary in GNU
+`troff'.  Nevertheless, they are supported.
+
+ -- Escape: \H'height'
+ -- Escape: \H'+height'
+ -- Escape: \H'-height'
+ -- Register: \n[.height]
+     Change (increment, decrement) the height of the current font, but
+     not the width.  If HEIGHT is zero, restore the original height.
+     Default scaling indicator is `z'.
+
+     The read-only number register `.height' contains the font height as
+     set by `\H'.
+
+     Currently, only the `-Tps' device supports this feature.
+
+     Note that `\H' doesn't produce an input token in `gtroff'.  As a
+     consequence, it can be used in requests like `mc' (which expects a
+     single character as an argument) to change the font on the fly:
+
+
+          .mc \H'+5z'x\H'0'
+
+     In compatibility mode, `gtroff' behaves differently:  If an
+     increment or decrement is used, it is always taken relative to the
+     current point size and not relative to the previously selected font
+     height.  Thus,
+
+
+          .cp 1
+          \H'+5'test \H'+5'test
+
+     prints the word `test' twice with the same font height (five
+     points larger than the current font size).
+
+ -- Escape: \S'slant'
+ -- Register: \n[.slant]
+     Slant the current font by SLANT degrees.  Positive values slant to
+     the right.  Only integer values are possible.
+
+     The read-only number register `.slant' contains the font slant as
+     set by `\S'.
+
+     Currently, only the `-Tps' device supports this feature.
+
+     Note that `\S' doesn't produce an input token in `gtroff'.  As a
+     consequence, it can be used in requests like `mc' (which expects a
+     single character as an argument) to change the font on the fly:
+
+
+          .mc \S'20'x\S'0'
+
+     This request is incorrectly documented in the original UNIX troff
+     manual; the slant is always set to an absolute value.
+
+ -- Request: .ul [lines]
+     The `ul' request normally underlines subsequent lines if a TTY
+     output device is used.  Otherwise, the lines are printed in italics
+     (only the term `underlined' is used in the following).  The single
+     argument is the number of input lines to be underlined; with no
+     argument, the next line is underlined.  If LINES is zero or
+     negative, stop the effects of `ul' (if it was active).  Requests
+     and empty lines do not count for computing the number of underlined
+     input lines, even if they produce some output like `tl'.  Lines
+     inserted by macros (e.g. invoked by a trap) do count.
+
+     At the beginning of `ul', the current font is stored and the
+     underline font is activated.  Within the span of a `ul' request,
+     it is possible to change fonts, but after the last line affected by
+     `ul' the saved font is restored.
+
+     This number of lines still to be underlined is associated with the
+     current environment (*note Environments::).  The underline font
+     can be changed with the `uf' request.
+
+     The `ul' request does not underline spaces.
+
+ -- Request: .cu [lines]
+     The `cu' request is similar to `ul' but underlines spaces as well
+     (if a TTY output device is used).
+
+ -- Request: .uf font
+     Set the underline font (globally) used by `ul' and `cu'.  By
+     default, this is the font at position 2.  FONT can be either a
+     non-negative font position or the name of a font.
+
+ -- Request: .bd font [offset]
+ -- Request: .bd font1 font2 [offset]
+ -- Register: \n[.b]
+     Artificially create a bold font by printing each glyph twice,
+     slightly offset.
+
+     Two syntax forms are available.
+
+        * Imitate a bold font unconditionally.  The first argument
+          specifies the font to embolden, and the second is the number
+          of basic units, minus one, by which the two glyphs are
+          offset.  If the second argument is missing, emboldening is
+          turned off.
+
+          FONT can be either a non-negative font position or the name
+          of a font.
+
+          OFFSET is available in the `.b' read-only register if a
+          special font is active; in the `bd' request, its default unit
+          is `u'.
+
+        * Imitate a bold form conditionally.  Embolden FONT1 by OFFSET
+          only if font FONT2 is the current font.  This command can be
+          issued repeatedly to set up different emboldening values for
+          different current fonts.  If the second argument is missing,
+          emboldening is turned off for this particular current font.
+
+          This affects special fonts only (either set up with the
+          `special' command in font files or with the `fspecial'
+          request).
+
+ -- Request: .cs font [width [em-size]]
+     Switch to and from "constant glyph space mode".  If activated, the
+     width of every glyph is WIDTH/36 ems.  The em size is given
+     absolutely by EM-SIZE; if this argument is missing, the em value
+     is taken from the current font size (as set with the `ps' request)
+     when the font is effectively in use.  Without second and third
+     argument, constant glyph space mode is deactivated.
+
+     Default scaling indicator for EM-SIZE is `z'; WIDTH is an integer.
+
+
+File: groff,  Node: Ligatures and Kerning,  Prev: Artificial Fonts,  Up: Fonts and Symbols
+
+5.17.7 Ligatures and Kerning
+----------------------------
+
+Ligatures are groups of characters that are run together, i.e, producing
+a single glyph.  For example, the letters `f' and `i' can form a
+ligature `fi' as in the word `file'.  This produces a cleaner look
+(albeit subtle) to the printed output.  Usually, ligatures are not
+available in fonts for TTY output devices.
+
+   Most POSTSCRIPT fonts support the fi and fl ligatures.  The C/A/T
+typesetter that was the target of AT&T `troff' also supported `ff',
+`ffi', and `ffl' ligatures.  Advanced typesetters or `expert' fonts may
+include ligatures for `ft' and `ct', although GNU `troff' does not
+support these (yet).
+
+   Only the current font is checked for ligatures and kerns; neither
+special fonts nor entities defined with the `char' request (and its
+siblings) are taken into account.
+
+ -- Request: .lg [flag]
+ -- Register: \n[.lg]
+     Switch the ligature mechanism on or off; if the parameter is
+     non-zero or missing, ligatures are enabled, otherwise disabled.
+     Default is on.  The current ligature mode can be found in the
+     read-only number register `.lg' (set to 1 or 2 if ligatures are
+     enabled, 0 otherwise).
+
+     Setting the ligature mode to 2 enables the two-character ligatures
+     (fi, fl, and ff) and disables the three-character ligatures (ffi
+     and ffl).
+
+   "Pairwise kerning" is another subtle typesetting mechanism that
+modifies the distance between a glyph pair to improve readability.  In
+most cases (but not always) the distance is decreased.  Typewriter-like
+fonts and fonts for terminals where all glyphs have the same width
+don't use kerning.
+
+ -- Request: .kern [flag]
+ -- Register: \n[.kern]
+     Switch kerning on or off.  If the parameter is non-zero or missing,
+     enable pairwise kerning, otherwise disable it.  The read-only
+     number register `.kern' is set to 1 if pairwise kerning is enabled,
+     0 otherwise.
+
+     If the font description file contains pairwise kerning information,
+     glyphs from that font are kerned.  Kerning between two glyphs can
+     be inhibited by placing `\&' between them: `V\&A'.
+
+     *Note Font File Format::.
+
+   "Track kerning" expands or reduces the space between glyphs.  This
+can be handy, for example, if you need to squeeze a long word onto a
+single line or spread some text to fill a narrow column.  It must be
+used with great care since it is usually considered bad typography if
+the reader notices the effect.
+
+ -- Request: .tkf f s1 n1 s2 n2
+     Enable track kerning for font F.  If the current font is F the
+     width of every glyph is increased by an amount between N1 and N2
+     (N1, N2 can be negative); if the current point size is less than
+     or equal to S1 the width is increased by N1; if it is greater than
+     or equal to S2 the width is increased by N2; if the point size is
+     greater than or equal to S1 and less than or equal to S2 the
+     increase in width is a linear function of the point size.
+
+     The default scaling indicator is `z' for S1 and S2, `p' for N1 and
+     N2.
+
+     Note that the track kerning amount is added even to the rightmost
+     glyph in a line; for large values it is thus recommended to
+     increase the line length by the same amount to compensate it.
+
+   Sometimes, when typesetting letters of different fonts, more or less
+space at such boundaries are needed.  There are two escapes to help
+with this.
+
+ -- Escape: \/
+     Increase the width of the preceding glyph so that the spacing
+     between that glyph and the following glyph is correct if the
+     following glyph is a roman glyph.  For example, if an italic `f'
+     is immediately followed by a roman right parenthesis, then in many
+     fonts the top right portion of the `f' overlaps the top left of
+     the right parenthesis.  Use this escape sequence whenever an
+     italic glyph is immediately followed by a roman glyph without any
+     intervening space.  This small amount of space is also called
+     "italic correction".
+
+
+ -- Escape: \,
+     Modify the spacing of the following glyph so that the spacing
+     between that glyph and the preceding glyph is correct if the
+     preceding glyph is a roman glyph.  Use this escape sequence
+     whenever a roman glyph is immediately followed by an italic glyph
+     without any intervening space.  In analogy to above, this space
+     could be called "left italic correction", but this term isn't used
+     widely.
+
+
+ -- Escape: \&
+     Insert a zero-width character, which is invisible.  Its intended
+     use is to stop interaction of a character with its surrounding.
+
+        * It prevents the insertion of extra space after an
+          end-of-sentence character.
+
+
+               Test.
+               Test.
+                   => Test.  Test.
+               Test.\&
+               Test.
+                   => Test. Test.
+
+        * It prevents interpretation of a control character at the
+          beginning of an input line.
+
+
+               .Test
+                   => warning: `Test' not defined
+               \&.Test
+                   => .Test
+
+        * It prevents kerning between two glyphs.
+
+        * It is needed to map an arbitrary character to nothing in the
+          `tr' request (*note Character Translations::).
+
+ -- Escape: \)
+     This escape is similar to `\&' except that it behaves like a
+     character declared with the `cflags' request to be transparent for
+     the purposes of an end-of-sentence character.
+
+     Its main usage is in macro definitions to protect against arguments
+     starting with a control character.
+
+
+          .de xxx
+          \)\\$1
+          ..
+          .de yyy
+          \&\\$1
+          ..
+          This is a test.\c
+          .xxx '
+          This is a test.
+              =>This is a test.'  This is a test.
+          This is a test.\c
+          .yyy '
+          This is a test.
+              =>This is a test.' This is a test.
+
+
+
+File: groff,  Node: Sizes,  Next: Strings,  Prev: Fonts and Symbols,  Up: gtroff Reference
+
+5.18 Sizes
+==========
+
+`gtroff' uses two dimensions with each line of text, type size and
+vertical spacing.  The "type size" is approximately the height of the
+tallest glyph.(1) (*note Sizes-Footnote-1::)  "Vertical spacing" is the
+amount of space `gtroff' allows for a line of text; normally, this is
+about 20% larger than the current type size.  Ratios smaller than this
+can result in hard-to-read text; larger than this, it spreads the text
+out more vertically (useful for term papers).  By default, `gtroff'
+uses 10 point type on 12 point spacing.
+
+   The difference between type size and vertical spacing is known, by
+typesetters, as "leading" (this is pronounced `ledding').
+
+* Menu:
+
+* Changing Type Sizes::
+* Fractional Type Sizes::
+
+
+File: groff,  Node: Sizes-Footnotes,  Up: Sizes
+
+   (1) This is usually the parenthesis.  Note that in most cases the
+real dimensions of the glyphs in a font are _not_ related to its type
+size!  For example, the standard POSTSCRIPT font families `Times
+Roman', `Helvetica', and `Courier' can't be used together at 10pt; to
+get acceptable output, the size of `Helvetica' has to be reduced by one
+point, and the size of `Courier' must be increased by one point.
+
+
+File: groff,  Node: Changing Type Sizes,  Next: Fractional Type Sizes,  Prev: Sizes,  Up: Sizes
+
+5.18.1 Changing Type Sizes
+--------------------------
+
+ -- Request: .ps [size]
+ -- Request: .ps +size
+ -- Request: .ps -size
+ -- Escape: \ssize
+ -- Register: \n[.s]
+     Use the `ps' request or the `\s' escape to change (increase,
+     decrease) the type size (in points).  Specify SIZE as either an
+     absolute point size, or as a relative change from the current size.
+     The size 0, or no argument, goes back to the previous size.
+
+     Default scaling indicator of `size' is `z'.  If `size' is zero or
+     negative, it is set to 1u.
+
+     The read-only number register `.s' returns the point size in
+     points as a decimal fraction.  This is a string.  To get the point
+     size in scaled points, use the `.ps' register instead.
+
+     `.s' is associated with the current environment (*note
+     Environments::).
+
+
+          snap, snap,
+          .ps +2
+          grin, grin,
+          .ps +2
+          wink, wink, \s+2nudge, nudge,\s+8 say no more!
+          .ps 10
+
+     The `\s' escape may be called in a variety of ways.  Much like
+     other escapes there must be a way to determine where the argument
+     ends and the text begins.  Any of the following forms are valid:
+
+    `\sN'
+          Set the point size to N points.  N must be either 0 or in the
+          range 4 to 39.
+
+    `\s+N'
+    `\s-N'
+          Increase or decrease the point size by N points.  N must be
+          exactly one digit.
+
+    `\s(NN'
+          Set the point size to NN points.  NN must be exactly two
+          digits.
+
+    `\s+(NN'
+    `\s-(NN'
+    `\s(+NN'
+    `\s(-NN'
+          Increase or decrease the point size by NN points.  NN must be
+          exactly two digits.
+
+     Note that `\s' doesn't produce an input token in `gtroff'.  As a
+     consequence, it can be used in requests like `mc' (which expects a
+     single character as an argument) to change the font on the fly:
+
+
+          .mc \s[20]x\s[0]
+
+     *Note Fractional Type Sizes::, for yet another syntactical form of
+     using the `\s' escape.
+
+ -- Request: .sizes s1 s2 ... sn [0]
+     Some devices may only have certain permissible sizes, in which case
+     `gtroff' rounds to the nearest permissible size.  The `DESC' file
+     specifies which sizes are permissible for the device.
+
+     Use the `sizes' request to change the permissible sizes for the
+     current output device.  Arguments are in scaled points; the
+     `sizescale' line in the `DESC' file for the output device provides
+     the scaling factor.  For example, if the scaling factor is 1000,
+     then the value 12000 is 12 points.
+
+     Each argument can be a single point size (such as `12000'), or a
+     range of sizes (such as `4000-72000').  You can optionally end the
+     list with a zero.
+
+ -- Request: .vs [space]
+ -- Request: .vs +space
+ -- Request: .vs -space
+ -- Register: \n[.v]
+     Change (increase, decrease) the vertical spacing by SPACE.  The
+     default scaling indicator is `p'.
+
+     If `vs' is called without an argument, the vertical spacing is
+     reset to the previous value before the last call to `vs'.
+
+     `gtroff' creates a warning of type `range' if SPACE is negative;
+     the vertical spacing is then set to smallest positive value, the
+     vertical resolution (as given in the `.V' register).
+
+     Note that `.vs 0' isn't saved in a diversion since it doesn't
+     result in a vertical motion.  You explicitly have to repeat this
+     command before inserting the diversion.
+
+     The read-only number register `.v' contains the current vertical
+     spacing; it is associated with the current environment (*note
+     Environments::).
+
+   The effective vertical line spacing consists of four components.
+Breaking a line causes the following actions (in the given order).
+
+   * Move the current point vertically by the "extra pre-vertical line
+     space".  This is the minimum value of all `\x' escapes with a
+     negative argument in the current output line.
+
+   * Move the current point vertically by the vertical line spacing as
+     set with the `vs' request.
+
+   * Output the current line.
+
+   * Move the current point vertically by the "extra post-vertical line
+     space".  This is the maximum value of all `\x' escapes with a
+     positive argument in the line which has just been output.
+
+   * Move the current point vertically by the "post-vertical line
+     spacing" as set with the `pvs' request.
+
+   It is usually better to use `vs' or `pvs' instead of `ls' to produce
+double-spaced documents: `vs' and `pvs' have a finer granularity for
+the inserted vertical space compared to `ls'; furthermore, certain
+preprocessors assume single-spacing.
+
+   *Note Manipulating Spacing::, for more details on the `\x' escape
+and the `ls' request.
+
+ -- Request: .pvs [space]
+ -- Request: .pvs +space
+ -- Request: .pvs -space
+ -- Register: \n[.pvs]
+     Change (increase, decrease) the post-vertical spacing by SPACE.
+     The default scaling indicator is `p'.
+
+     If `pvs' is called without an argument, the post-vertical spacing
+     is reset to the previous value before the last call to `pvs'.
+
+     `gtroff' creates a warning of type `range' if SPACE is zero or
+     negative; the vertical spacing is then set to zero.
+
+     The read-only number register `.pvs' contains the current
+     post-vertical spacing; it is associated with the current
+     environment (*note Environments::).
+
+
+File: groff,  Node: Fractional Type Sizes,  Prev: Changing Type Sizes,  Up: Sizes
+
+5.18.2 Fractional Type Sizes
+----------------------------
+
+A "scaled point" is equal to 1/SIZESCALE points, where SIZESCALE is
+specified in the `DESC' file (1 by default).  There is a new scale
+indicator `z' which has the effect of multiplying by SIZESCALE.
+Requests and escape sequences in `gtroff' interpret arguments that
+represent a point size as being in units of scaled points, but they
+evaluate each such argument using a default scale indicator of `z'.
+Arguments treated in this way are the argument to the `ps' request, the
+third argument to the `cs' request, the second and fourth arguments to
+the `tkf' request, the argument to the `\H' escape sequence, and those
+variants of the `\s' escape sequence that take a numeric expression as
+their argument (see below).
+
+   For example, suppose SIZESCALE is 1000; then a scaled point is
+equivalent to a millipoint; the request `.ps 10.25' is equivalent to
+`.ps 10.25z' and thus sets the point size to 10250 scaled points, which
+is equal to 10.25 points.
+
+   `gtroff' disallows the use of the `z' scale indicator in instances
+where it would make no sense, such as a numeric expression whose
+default scale indicator was neither `u' nor `z'.  Similarly it would
+make no sense to use a scaling indicator other than `z' or `u' in a
+numeric expression whose default scale indicator was `z', and so
+`gtroff' disallows this as well.
+
+   There is also new scale indicator `s' which multiplies by the number
+of units in a scaled point.  So, for example, `\n[.ps]s' is equal to
+`1m'.  Be sure not to confuse the `s' and `z' scale indicators.
+
+ -- Register: \n[.ps]
+     A read-only number register returning the point size in scaled
+     points.
+
+     `.ps' is associated with the current environment (*note
+     Environments::).
+
+ -- Register: \n[.psr]
+ -- Register: \n[.sr]
+     The last-requested point size in scaled points is contained in the
+     `.psr' read-only number register.  The last requested point size
+     in points as a decimal fraction can be found in `.sr'.  This is a
+     string-valued read-only number register.
+
+     Note that the requested point sizes are device-independent, whereas
+     the values returned by the `.ps' and `.s' registers are not.  For
+     example, if a point size of 11pt is requested, and a `sizes'
+     request (or a `sizescale' line in a `DESC' file) specifies 10.95pt
+     instead, this value is actually used.
+
+     Both registers are associated with the current environment (*note
+     Environments::).
+
+   The `\s' escape has the following syntax for working with fractional
+type sizes:
+
+`\s[N]'
+`\s'N''
+     Set the point size to N scaled points; N is a numeric expression
+     with a default scale indicator of `z'.
+
+`\s[+N]'
+`\s[-N]'
+`\s+[N]'
+`\s-[N]'
+`\s'+N''
+`\s'-N''
+`\s+'N''
+`\s-'N''
+     Increase or or decrease the point size by N scaled points; N is a
+     numeric expression with a default scale indicator of `z'.
+
+   *Note Font Files::.
+
+
+File: groff,  Node: Strings,  Next: Conditionals and Loops,  Prev: Sizes,  Up: gtroff Reference
+
+5.19 Strings
+============
+
+`gtroff' has string variables, which are entirely for user convenience
+(i.e. there are no built-in strings exept `.T', but even this is a
+read-write string variable).
+
+ -- Request: .ds name [string]
+ -- Request: .ds1 name [string]
+ -- Escape: \*n
+ -- Escape: \*(nm
+ -- Escape: \*[name arg1 arg2 ...]
+     Define and access a string variable NAME (one-character name N,
+     two-character name NM).  If NAME already exists, `ds' overwrites
+     the previous definition.  Only the syntax form using brackets can
+     take arguments which are handled identically to macro arguments;
+     the single exception is that a closing bracket as an argument must
+     be enclosed in double quotes.  *Note Request and Macro
+     Arguments::, and *Note Parameters::.
+
+     Example:
+
+
+          .ds foo a \\$1 test
+          .
+          This is \*[foo nice].
+              => This is a nice test.
+
+     The `\*' escape "interpolates" (expands in-place) a
+     previously-defined string variable.  To be more precise, the stored
+     string is pushed onto the input stack which is then parsed by
+     `gtroff'.  Similar to number registers, it is possible to nest
+     strings, i.e. string variables can be called within string
+     variables.
+
+     If the string named by the `\*' escape does not exist, it is
+     defined as empty, and a warning of type `mac' is emitted (see
+     *Note Debugging::, for more details).
+
+     *Caution:* Unlike other requests, the second argument to the `ds'
+     request takes up the entire line including trailing spaces.  This
+     means that comments on a line with such a request can introduce
+     unwanted space into a string.
+
+
+          .ds UX \s-1UNIX\s0\u\s-3tm\s0\d \" UNIX trademark
+
+     Instead the comment should be put on another line or have the
+     comment escape adjacent with the end of the string.
+
+
+          .ds UX \s-1UNIX\s0\u\s-3tm\s0\d\"  UNIX trademark
+
+     To produce leading space the string can be started with a double
+     quote.  No trailing quote is needed; in fact, any trailing quote is
+     included in your string.
+
+
+          .ds sign "           Yours in a white wine sauce,
+
+     Strings are not limited to a single line of text.  A string can
+     span several lines by escaping the newlines with a backslash.  The
+     resulting string is stored _without_ the newlines.
+
+
+          .ds foo lots and lots \
+          of text are on these \
+          next several lines
+
+     It is not possible to have real newlines in a string.  To put a
+     single double quote character into a string, use two consecutive
+     double quote characters.
+
+     The `ds1' request turns off compatibility mode while interpreting
+     a string.  To be more precise, a "compatibility save" input token
+     is inserted at the beginning of  the string, and a "compatibility
+     restore" input token at the end.
+
+
+          .nr xxx 12345
+          .ds aa The value of xxx is \\n[xxx].
+          .ds1 bb The value of xxx ix \\n[xxx].
+          .
+          .cp 1
+          .
+          \*(aa
+              => warning: number register `[' not defined
+              => The value of xxx is 0xxx].
+          \*(bb
+              => The value of xxx ix 12345.
+
+     Strings, macros, and diversions (and boxes) share the same name
+     space.  Internally, even the same mechanism is used to store them.
+     This has some interesting consequences.  For example, it is
+     possible to call a macro with string syntax and vice versa.
+
+
+          .de xxx
+          a funny test.
+          ..
+          This is \*[xxx]
+              => This is a funny test.
+
+          .ds yyy a funny test
+          This is
+          .yyy
+              => This is a funny test.
+
+     Diversions and boxes can be also called with string syntax.
+
+     Another consequence is that you can copy one-line diversions or
+     boxes to a string.
+
+
+          .di xxx
+          a \fItest\fR
+          .br
+          .di
+          .ds yyy This is \*[xxx]\c
+          \*[yyy].
+              => This is a test.
+
+     As the previous example shows, it is possible to store formatted
+     output in strings.  The `\c' escape prevents the insertion of an
+     additional blank line in the output.
+
+     Copying diversions longer than a single output line produces
+     unexpected results.
+
+
+          .di xxx
+          a funny
+          .br
+          test
+          .br
+          .di
+          .ds yyy This is \*[xxx]\c
+          \*[yyy].
+              => test This is a funny.
+
+     Usually, it is not predictable whether a diversion contains one or
+     more output lines, so this mechanism should be avoided.  With UNIX
+     `troff', this was the only solution to strip off a final newline
+     from a diversion.  Another disadvantage is that the spaces in the
+     copied string are already formatted, making them unstretchable.
+     This can cause ugly results.
+
+     A clean solution to this problem is available in GNU `troff',
+     using the requests `chop' to remove the final newline of a
+     diversion, and `unformat' to make the horizontal spaces
+     stretchable again.
+
+
+          .box xxx
+          a funny
+          .br
+          test
+          .br
+          .box
+          .chop xxx
+          .unformat xxx
+          This is \*[xxx].
+              => This is a funny test.
+
+     *Note Gtroff Internals::, for more information.
+
+ -- Request: .as name [string]
+ -- Request: .as1 name [string]
+     The `as' request is similar to `ds' but appends STRING to the
+     string stored as NAME instead of redefining it.  If NAME doesn't
+     exist yet, it is created.
+
+
+          .as sign " with shallots, onions and garlic,
+
+     The `as1' request is similar to `as', but compatibility mode is
+     switched off while the appended string is interpreted.  To be more
+     precise, a "compatibility save" input token is inserted at the
+     beginning of the appended string, and a "compatibility restore"
+     input token at the end.
+
+   Rudimentary string manipulation routines are given with the next two
+requests.
+
+ -- Request: .substring str n1 [n2]
+     Replace the string named STR with the substring defined by the
+     indices N1 and N2.  The first character in the string has index 0.
+     If N2 is omitted, it is taken to be equal to the string's length.
+     If the index value N1 or N2 is negative, it is counted from the
+     end of the string, going backwards: The last character has
+     index -1, the character before the last character has index -2,
+     etc.
+
+
+          .ds xxx abcdefgh
+          .substring xxx 1 -4
+          \*[xxx]
+              => bcde
+
+
+ -- Request: .length reg str
+     Compute the number of characters of STR and return it in the
+     number register REG.  If REG doesn't exist, it is created.  `str'
+     is read in copy mode.
+
+
+          .ds xxx abcd\h'3i'efgh
+          .length yyy \*[xxx]
+          \n[yyy]
+              => 14
+
+
+ -- Request: .rn xx yy
+     Rename the request, macro, diversion, or string XX to YY.
+
+ -- Request: .rm xx
+     Remove the request, macro, diversion, or string XX.  `gtroff'
+     treats subsequent invocations as if the object had never been
+     defined.
+
+ -- Request: .als new old
+     Create an alias named NEW for the request, string, macro, or
+     diversion object named OLD.  The new name and the old name are
+     exactly equivalent (it is similar to a hard rather than a soft
+     link). If OLD is undefined, `gtroff' generates a warning of type
+     `mac' and ignores the request.
+
+ -- Request: .chop xx
+     Remove (chop) the last character from the macro, string, or
+     diversion named XX.  This is useful for removing the newline from
+     the end of diversions that are to be interpolated as strings.
+     This command can be used repeatedly; see *Note Gtroff Internals::,
+     for details on nodes inserted additionally by `gtroff'.
+
+   *Note Identifiers::, and *Note Comments::.
+
+
+File: groff,  Node: Conditionals and Loops,  Next: Writing Macros,  Prev: Strings,  Up: gtroff Reference
+
+5.20 Conditionals and Loops
+===========================
+
+* Menu:
+
+* Operators in Conditionals::
+* if-else::
+* while::
+
+
+File: groff,  Node: Operators in Conditionals,  Next: if-else,  Prev: Conditionals and Loops,  Up: Conditionals and Loops
+
+5.20.1 Operators in Conditionals
+--------------------------------
+
+In `if' and `while' requests, there are several more operators
+available:
+
+`e'
+`o'
+     True if the current page is even or odd numbered (respectively).
+
+`n'
+     True if the document is being processed in nroff mode (i.e., the
+     `.nroff' command has been issued).
+
+`t'
+     True if the document is being processed in troff mode (i.e., the
+     `.troff' command has been issued).
+
+`v'
+     Always false.  This condition is for compatibility with other
+     `troff' versions only (identifying a `-Tversatec' device).
+
+`'XXX'YYY''
+     True if the string XXX is equal to the string YYY.  Other
+     characters can be used in place of the single quotes; the same set
+     of delimiters as for the `\D' escape is used (*note Escapes::).
+     `gtroff' formats the strings before being compared:
+
+
+          .ie "|"\fR|\fP" \
+          true
+          .el \
+          false
+              => true
+
+     The resulting motions, glyph sizes, and fonts have to match,(1)
+     (*note Operators in Conditionals-Footnote-1::) and not the
+     individual motion, size, and font requests.  In the previous
+     example, `|' and `\fR|\fP' both result in a roman `|' glyph with
+     the same point size and at the same location on the page, so the
+     strings are equal.  If `.ft I' had been added before the `.ie',
+     the result would be "false" because (the first) `|' produces an
+     italic `|' rather than a roman one.
+
+`r XXX'
+     True if there is a number register named XXX.
+
+`d XXX'
+     True if there is a string, macro, diversion, or request named XXX.
+
+`m XXX'
+     True if there is a color named XXX.
+
+`c G'
+     True if there is a glyph G available(2) (*note Operators in
+     Conditionals-Footnote-2::); G is either an ASCII character or a
+     special character (`\(GG' or `\[GGG]'); the condition is also true
+     if G has been defined by the `char' request.
+
+`F FONT'
+     True if a font named FONT exists.  FONT is handled as if it was
+     opened with the `ft' request (this is, font translation and styles
+     are applied), without actually mounting it.
+
+     This test doesn't load the complete font but only its header to
+     verify its validity.
+
+`S STYLE'
+     True if style STYLE has been registered.  Font translation is
+     applied.
+
+   Note that these operators can't be combined with other operators like
+`:' or `&'; only a leading `!' (without whitespace between the
+exclamation mark and the operator) can be used to negate the result.
+
+
+     .nr xxx 1
+     .ie !r xxx \
+     true
+     .el \
+     false
+         => false
+
+   A whitespace after `!' always evaluates to zero (this bizarre
+behaviour is due to compatibility with UNIX `troff').
+
+
+     .nr xxx 1
+     .ie ! r xxx \
+     true
+     .el \
+     false
+         => r xxx true
+
+   It is possible to omit the whitespace before the argument to the
+`r', `d', and `c' operators.
+
+   *Note Expressions::.
+
+
+File: groff,  Node: Operators in Conditionals-Footnotes,  Up: Operators in Conditionals
+
+   (1) The created output nodes must be identical.  *Note Gtroff
+Internals::.
+
+   (2) The name of this conditional operator is a misnomer since it
+tests names of output glyphs.
+
+
+File: groff,  Node: if-else,  Next: while,  Prev: Operators in Conditionals,  Up: Conditionals and Loops
+
+5.20.2 if-else
+--------------
+
+`gtroff' has if-then-else constructs like other languages, although the
+formatting can be painful.
+
+ -- Request: .if expr anything
+     Evaluate the expression EXPR, and executes ANYTHING (the remainder
+     of the line) if EXPR evaluates to a value greater than zero
+     (true).  ANYTHING is interpreted as though it was on a line by
+     itself (except that leading spaces are swallowed).  *Note
+     Expressions::, for more info.
+
+
+          .nr xxx 1
+          .nr yyy 2
+          .if ((\n[xxx] == 1) & (\n[yyy] == 2)) true
+              => true
+
+
+ -- Request: .nop anything
+     Executes ANYTHING.  This is similar to `.if 1'.
+
+ -- Request: .ie expr anything
+ -- Request: .el anything
+     Use the `ie' and `el' requests to write an if-then-else.  The
+     first request is the `if' part and the latter is the `else' part.
+
+
+          .ie n .ls 2 \" double-spacing in nroff
+          .el   .ls 1 \" single-spacing in troff
+
+
+ -- Escape: \{
+ -- Escape: \}
+     In many cases, an if (or if-else) construct needs to execute more
+     than one request.  This can be done using the `\{' and `\}'
+     escapes.  The following example shows the possible ways to use
+     these escapes (note the position of the opening and closing
+     braces).
+
+
+          .ie t \{\
+          .    ds lq ``
+          .    ds rq ''
+          .\}
+          .el \
+          .\{\
+          .    ds lq "
+          .    ds rq "\}
+
+
+   *Note Expressions::.
+
+
+File: groff,  Node: while,  Prev: if-else,  Up: Conditionals and Loops
+
+5.20.3 while
+------------
+
+`gtroff' provides a looping construct using the `while' request, which
+is used much like the `if' (and related) requests.
+
+ -- Request: .while expr anything
+     Evaluate the expression EXPR, and repeatedly execute ANYTHING (the
+     remainder of the line) until EXPR evaluates to 0.
+
+
+          .nr a 0 1
+          .while (\na < 9) \{\
+          \n+a,
+          .\}
+          \n+a
+              => 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
+
+     Some remarks.
+
+        * The body of a `while' request is treated like the body of a
+          `de' request: `gtroff' temporarily stores it in a macro which
+          is deleted after the loop has been exited.  It can
+          considerably slow down a macro if the body of the `while'
+          request (within the macro) is large.  Each time the macro is
+          executed, the `while' body is parsed and stored again as a
+          temporary macro.
+
+
+               .de xxx
+               .  nr num 10
+               .  while (\\n[num] > 0) \{\
+               .    \" many lines of code
+               .    nr num -1
+               .  \}
+               ..
+
+          The traditional and ofter better solution (UNIX `troff'
+          doesn't have the `while' request) is to use a recursive macro
+          instead which is parsed only once during its definition.
+
+
+               .de yyy
+               .  if (\\n[num] > 0) \{\
+               .    \" many lines of code
+               .    nr num -1
+               .    yyy
+               .  \}
+               ..
+               .
+               .de xxx
+               .  nr num 10
+               .  yyy
+               ..
+
+          Note that the number of available recursion levels is set
+          to 1000 (this is a compile-time constant value of `gtroff').
+
+        * The closing brace of a `while' body must end a line.
+
+
+               .if 1 \{\
+               .  nr a 0 1
+               .  while (\n[a] < 10) \{\
+               .    nop \n+[a]
+               .\}\}
+                   => unbalanced \{ \}
+
+
+ -- Request: .break
+     Break out of a `while' loop.  Be sure not to confuse this with the
+     `br' request (causing a line break).
+
+ -- Request: .continue
+     Finish the current iteration of a `while' loop, immediately
+     restarting the next iteration.
+
+   *Note Expressions::.
+
+
+File: groff,  Node: Writing Macros,  Next: Page Motions,  Prev: Conditionals and Loops,  Up: gtroff Reference
+
+5.21 Writing Macros
+===================
+
+A "macro" is a collection of text and embedded commands which can be
+invoked multiple times.  Use macros to define common operations.
+
+ -- Request: .de name [end]
+ -- Request: .de1 name [end]
+ -- Request: .dei name [end]
+ -- Request: .dei1 name [end]
+     Define a new macro named NAME.  `gtroff' copies subsequent lines
+     (starting with the next one) into an internal buffer until it
+     encounters the line `..' (two dots).  The optional second argument
+     to `de' changes this to a macro to `.END'.
+
+     There can be whitespace after the first dot in the line containing
+     the ending token (either `.' or macro `END').
+
+     Here a small example macro called `P' which causes a break and
+     inserts some vertical space.  It could be used to separate
+     paragraphs.
+
+
+          .de P
+          .  br
+          .  sp .8v
+          ..
+
+     The following example defines a macro within another.  Remember
+     that expansion must be protected twice; once for reading the macro
+     and once for executing.
+
+
+          \# a dummy macro to avoid a warning
+          .de end
+          ..
+          .
+          .de foo
+          .  de bar end
+          .    nop \f[B]Hallo \\\\$1!\f[]
+          .  end
+          ..
+          .
+          .foo
+          .bar Joe
+              => Hallo Joe!
+
+     Since `\f' has no expansion, it isn't necessary to protect its
+     backslash.  Had we defined another macro within `bar' which takes
+     a parameter, eight backslashes would be necessary before `$1'.
+
+     The `de1' request turns off compatibility mode while executing the
+     macro.  On entry, the current compatibility mode is saved and
+     restored at exit.
+
+
+          .nr xxx 12345
+          .
+          .de aa
+          The value of xxx is \\n[xxx].
+          ..
+          .de1 bb
+          The value of xxx ix \\n[xxx].
+          ..
+          .
+          .cp 1
+          .
+          .aa
+              => warning: number register `[' not defined
+              => The value of xxx is 0xxx].
+          .bb
+              => The value of xxx ix 12345.
+
+     The `dei' request defines a macro indirectly.  That is, it expands
+     strings whose names are NAME or END before performing the append.
+
+     This:
+
+
+          .ds xx aa
+          .ds yy bb
+          .dei xx yy
+
+     is equivalent to:
+
+
+          .de aa bb
+
+     The `dei1' request is similar to `dei' but with compatibility mode
+     switched off during execution of the defined macro.
+
+     If compatibility mode is on, `de' (and `dei') behave similar to
+     `de1' (and `dei1'): A `compatibility save' token is inserted at
+     the beginning, and a `compatibility restore' token at the end, with
+     compatibility mode switched on during execution.  *Note Gtroff
+     Internals::, for more information on switching compatibility mode
+     on and off in a single document.
+
+     Using `trace.tmac', you can trace calls to `de' and `de1'.
+
+     Note that macro identifiers are shared with identifiers for
+     strings and diversions.
+
+ -- Request: .am name [end]
+ -- Request: .am1 name [end]
+ -- Request: .ami name [end]
+ -- Request: .ami1 name [end]
+     Works similarly to `de' except it appends onto the macro named
+     NAME.  So, to make the previously defined `P' macro actually do
+     indented instead of block paragraphs, add the necessary code to the
+     existing macro like this:
+
+
+          .am P
+          .ti +5n
+          ..
+
+     The `am1' request turns off compatibility mode while executing the
+     appended macro piece.  To be more precise, a "compatibility save"
+     input token is inserted at the beginning of the appended code, and
+     a "compatibility restore" input token at the end.
+
+     The `ami' request appends indirectly, meaning that `gtroff'
+     expands strings whose names are NAME or END before performing the
+     append.
+
+     The `ami1' request is similar to `ami' but compatibility mode is
+     switched off during execution of the defined macro.
+
+     Using `trace.tmac', you can trace calls to `am' and `am1'.
+
+   *Note Strings::, for the `als' request to rename a macro.
+
+   The `de', `am', `di', `da', `ds', and `as' requests (together with
+its variants) only create a new object if the name of the macro,
+diversion or string diversion is currently undefined or if it is
+defined to be a request; normally they modify the value of an existing
+object.
+
+ -- Request: .return [anything]
+     Exit a macro, immediately returning to the caller.
+
+     If called with an argument, exit twice, namely the current macro
+     and the macro one level higher.  This is used to define a wrapper
+     macro for `return' in `trace.tmac'.
+
+* Menu:
+
+* Copy-in Mode::
+* Parameters::
+
+
+File: groff,  Node: Copy-in Mode,  Next: Parameters,  Prev: Writing Macros,  Up: Writing Macros
+
+5.21.1 Copy-in Mode
+-------------------
+
+When `gtroff' reads in the text for a macro, string, or diversion, it
+copies the text (including request lines, but excluding escapes) into
+an internal buffer.  Escapes are converted into an internal form,
+except for `\n', `\$', `\*', `\\' and `\<RET>' which are evaluated and
+inserted into the text where the escape was located.  This is known as
+"copy-in" mode or "copy" mode.
+
+   What this means is that you can specify when these escapes are to be
+evaluated (either at copy-in time or at the time of use) by insulating
+the escapes with an extra backslash.  Compare this to the `\def' and
+`\edef' commands in TeX.
+
+   The following example prints the numbers 20 and 10:
+
+
+     .nr x 20
+     .de y
+     .nr x 10
+     \&\nx
+     \&\\nx
+     ..
+     .y
+
+
+File: groff,  Node: Parameters,  Prev: Copy-in Mode,  Up: Writing Macros
+
+5.21.2 Parameters
+-----------------
+
+The arguments to a macro or string can be examined using a variety of
+escapes.
+
+ -- Register: \n[.$]
+     The number of arguments passed to a macro or string.  This is a
+     read-only number register.
+
+     Note that the `shift' request can change its value.
+
+   Any individual argument can be retrieved with one of the following
+escapes:
+
+ -- Escape: \$n
+ -- Escape: \$(nn
+ -- Escape: \$[nnn]
+     Retrieve the Nth, NNth or NNNth argument.  As usual, the first
+     form only accepts a single number (larger than zero), the second a
+     two-digit number (larger or equal to 10), and the third any
+     positive integer value (larger than zero).  Macros and strings can
+     have an unlimited number of arguments.  Note that due to copy-in
+     mode, use two backslashes on these in actual use to prevent
+     interpolation until the macro is actually invoked.
+
+ -- Request: .shift [n]
+     Shift the arguments 1 position, or as many positions as specified
+     by its argument.  After executing this request, argument I becomes
+     argument I-N; arguments 1 to N are no longer available.  Shifting
+     by negative amounts is currently undefined.
+
+     The register `.$' is adjusted accordingly.
+
+ -- Escape: \$*
+ -- Escape: \$@
+     In some cases it is convenient to use all of the arguments at once
+     (for example, to pass the arguments along to another macro).  The
+     `\$*' escape concatenates all the arguments separated by spaces.  A
+     similar escape is `\$@', which concatenates all the arguments with
+     each surrounded by double quotes, and separated by spaces.  If not
+     in compatibility mode, the input level of double quotes is
+     preserved (see *Note Request and Macro Arguments::).
+
+ -- Escape: \$0
+     The name used to invoke the current macro.  The `als' request can
+     make a macro have more than one name.
+
+
+          .de generic-macro
+          .  ...
+          .  if \\n[error] \{\
+          .    tm \\$0: Houston, we have a problem.
+          .    return
+          .  \}
+          ..
+          .
+          .als foo generic-macro
+          .als bar generic-macro
+
+
+   *Note Request and Macro Arguments::.
+
+
+File: groff,  Node: Page Motions,  Next: Drawing Requests,  Prev: Writing Macros,  Up: gtroff Reference
+
+5.22 Page Motions
+=================
+
+*Note Manipulating Spacing::, for a discussion of the main request for
+vertical motion, `sp'.
+
+ -- Request: .mk [reg]
+ -- Request: .rt [dist]
+     The request `mk' can be used to mark a location on a page, for
+     movement to later.  This request takes a register name as an
+     argument in which to store the current page location.  With no
+     argument it stores the location in an internal register.  The
+     results of this can be used later by the `rt' or the `sp' request
+     (or the `\v' escape).
+
+     The `rt' request returns _upwards_ to the location marked with the
+     last `mk' request.  If used with an argument, return to a position
+     which distance from the top of the page is DIST (no previous call
+     to `mk' is necessary in this case).  Default scaling indicator is
+     `v'.
+
+     Here a primitive solution for a two-column macro.
+
+
+          .nr column-length 1.5i
+          .nr column-gap 4m
+          .nr bottom-margin 1m
+          .
+
+
+          .de 2c
+          .  br
+          .  mk
+          .  ll \\n[column-length]u
+          .  wh -\\n[bottom-margin]u 2c-trap
+          .  nr right-side 0
+          ..
+          .
+
+
+          .de 2c-trap
+          .  ie \\n[right-side] \{\
+          .    nr right-side 0
+          .    po -(\\n[column-length]u + \\n[column-gap]u)
+          .    \" remove trap
+          .    wh -\\n[bottom-margin]u
+          .  \}
+          .  el \{\
+          .    \" switch to right side
+          .    nr right-side 1
+          .    po +(\\n[column-length]u + \\n[column-gap]u)
+          .    rt
+          .  \}
+          ..
+          .
+
+
+          .pl 1.5i
+          .ll 4i
+          This is a small test which shows how the
+          rt request works in combination with mk.
+
+          .2c
+          Starting here, text is typeset in two columns.
+          Note that this implementation isn't robust
+          and thus not suited for a real two-column
+          macro.
+
+     Result:
+
+
+          This is a small test which shows how the
+          rt request works in combination with mk.
+
+          Starting  here,    isn't    robust
+          text is typeset    and   thus  not
+          in two columns.    suited  for   a
+          Note that  this    real two-column
+          implementation     macro.
+
+
+   The following escapes give fine control of movements about the page.
+
+ -- Escape: \v'e'
+     Move vertically, usually from the current location on the page (if
+     no absolute position operator `|' is used).  The argument E
+     specifies the distance to move; positive is downwards and negative
+     upwards.  The default scaling indicator for this escape is `v'.
+     Beware, however, that `gtroff' continues text processing at the
+     point where the motion ends, so you should always balance motions
+     to avoid interference with text processing.
+
+     `\v' doesn't trigger a trap.  This can be quite useful; for
+     example, consider a page bottom trap macro which prints a marker
+     in the margin to indicate continuation of a footnote or something
+     similar.
+
+   There are some special-case escapes for vertical motion.
+
+ -- Escape: \r
+     Move upwards 1v.
+
+ -- Escape: \u
+     Move upwards .5v.
+
+ -- Escape: \d
+     Move down .5v.
+
+ -- Escape: \h'e'
+     Move horizontally, usually from the current location (if no
+     absolute position operator `|' is used).  The expression E
+     indicates how far to move: positive is rightwards and negative
+     leftwards.  The default scaling indicator for this escape is `m'.
+
+     This horizontal space is not discarded at the end of a line.  To
+     insert discardable space of a certain length use the `ss' request.
+
+   There are a number of special-case escapes for horizontal motion.
+
+ -- Escape: \<SP>
+     An unbreakable and unpaddable (i.e. not expanded during filling)
+     space.  (Note: This is a backslash followed by a space.)
+
+ -- Escape: \~
+     An unbreakable space that stretches like a normal inter-word space
+     when a line is adjusted.
+
+ -- Escape: \|
+     A 1/6th em space.  Ignored for TTY output devices (rounded to
+     zero).
+
+ -- Escape: \^
+     A 1/12th em space.  Ignored for TTY output devices (rounded to
+     zero).
+
+ -- Escape: \0
+     A space the size of a digit.
+
+   The following string sets the TeX logo:
+
+
+     .ds TeX T\h'-.1667m'\v'.224m'E\v'-.224m'\h'-.125m'X
+
+ -- Escape: \w'text'
+ -- Register: \n[st]
+ -- Register: \n[sb]
+ -- Register: \n[rst]
+ -- Register: \n[rsb]
+ -- Register: \n[ct]
+ -- Register: \n[ssc]
+ -- Register: \n[skw]
+     Return the width of the specified TEXT in basic units.  This
+     allows horizontal movement based on the width of some arbitrary
+     text (e.g. given as an argument to a macro).
+
+
+          The length of the string `abc' is \w'abc'u.
+              => The length of the string `abc' is 72u.
+
+     Font changes may occur in TEXT which don't affect current settings.
+
+     After use, `\w' sets several registers:
+
+    `st'
+    `sb'
+          The highest and lowest point of the baseline, respectively,
+          in TEXT.
+
+    `rst'
+    `rsb'
+          Like the `st' and `sb' registers, but takes account of the
+          heights and depths of glyphs.  With other words, this gives
+          the highest and lowest point of TEXT.  Values below the
+          baseline are negative.
+
+    `ct'
+          Defines the kinds of glyphs occurring in TEXT:
+
+         0
+               only short glyphs, no descenders or tall glyphs.
+
+         1
+               at least one descender.
+
+         2
+               at least one tall glyph.
+
+         3
+               at least one each of a descender and a tall glyph.
+
+    `ssc'
+          The amount of horizontal space (possibly negative) that
+          should be added to the last glyph before a subscript.
+
+    `skw'
+          How far to right of the center of the last glyph in the `\w'
+          argument, the center of an accent from a roman font should be
+          placed over that glyph.
+
+ -- Escape: \kp
+ -- Escape: \k(ps
+ -- Escape: \k[position]
+     Store the current horizontal position in the _input_ line in
+     number register with name POSITION (one-character name P,
+     two-character name PS).  Use this, for example, to return to the
+     beginning of a string for highlighting or other decoration.
+
+ -- Register: \n[hp]
+     The current horizontal position at the input line.
+
+ -- Register: \n[.k]
+     A read-only number register containing the current horizontal
+     output position (relative to the current indentation).
+
+ -- Escape: \o'abc'
+     Overstrike glyphs A, B, C, ...; the glyphs are centered, and the
+     resulting spacing is the largest width of the affected glyphs.
+
+ -- Escape: \zg
+     Print glyph G with zero width, i.e., without spacing.  Use this to
+     overstrike glyphs left-aligned.
+
+ -- Escape: \Z'anything'
+     Print ANYTHING, then restore the horizontal and vertical position.
+     The argument may not contain tabs or leaders.
+
+     The following is an example of a strike-through macro:
+
+
+          .de ST
+          .nr ww \w'\\$1'
+          \Z@\v'-.25m'\l'\\n[ww]u'@\\$1
+          ..
+          .
+          This is
+          .ST "a test"
+          an actual emergency!
+
+
+
+
+Local Variables:
+coding: iso-8859-1
+End: