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diff --git a/share/doc/usd/22.trofftut/tt02 b/share/doc/usd/22.trofftut/tt02 new file mode 100644 index 0000000..95ef0af --- /dev/null +++ b/share/doc/usd/22.trofftut/tt02 @@ -0,0 +1,208 @@ +.\" This module is believed to contain source code proprietary to AT&T. +.\" Use and redistribution is subject to the Berkeley Software License +.\" Agreement and your Software Agreement with AT&T (Western Electric). +.\" +.\" @(#)tt02 8.1 (Berkeley) 6/8/93 +.\" +.\" $FreeBSD$ +.NH +Point Sizes; Line Spacing +.PP +As mentioned above, +the command +.BD .ps +sets the point size. +One point is 1/72 inch, +so 6-point characters are at most 1/12 inch high, +and 36-point characters are \(12 inch. +There are 15 point sizes, listed below. +.P1 1 +.ps 6 +6 point: Pack my box with five dozen liquor jugs. +.ps 7 +.vs 8p +7 point: Pack my box with five dozen liquor jugs. +.vs 9p +.ps 8 +8 point: Pack my box with five dozen liquor jugs. +.vs 10p +.ps 9 +9 point: Pack my box with five dozen liquor jugs. +.vs 11p +.ps 10 +10 point: Pack my box with five dozen liquor +.vs 12p +.ps 11 +11 point: Pack my box with five dozen +.vs 14p +.ps 12 +12 point: Pack my box with five dozen +.vs 16p +.ps 14 +14 point: Pack my box with five +.vs 24p +\s1616 point\s18 18 point\s20 20 point +.vs 40p +\s2222\s24 24\s28 28\s36 36 +.ps 10 +.vs 12p +.P2 +.PP +If the number after +.BD .ps +is not one of these +legal sizes, +it is rounded up to the next valid value, +with a maximum of 36. +If no number follows +.BD .ps , +.UL troff +reverts to the previous size, whatever it was. +.UL troff +begins with point size 10, +which is usually fine. +The original of this document (on 8.5 by 11 inch paper) is in 9 point. +.PP +The point size can also be changed in the middle of a line +or even a word +with the in-line command +.BD \es . +To produce +.P1 +\s8UNIX\s10 runs on a \s8PDP-\s1011/45 +.P2 +type +.P1 +\es8UNIX\es10 runs on a \es8PDP-\es1011/45 +.P2 +As above, +.BD \es +should be followed by a legal point size, +except that +.BD \es0 +causes the size to revert to +its previous value. +Notice that +.BD \es1011 +can be understood correctly as `size 10, followed by an 11', if the size is legal, +but not otherwise. +Be cautious with similar constructions. +.PP +Relative size changes are also legal and useful: +.P1 +\es\-2UNIX\es+2 +.P2 +temporarily decreases the size, whatever it is, by two points, then +restores it. +Relative size changes have the advantage that the size difference +is independent of the starting size of the document. +The amount of the relative change is restricted +to a single digit. +.WS +.PP +The other parameter that determines what the type looks like +is the spacing between lines, +which is set independently of the point size. +Vertical spacing is measured from the bottom of one line to +the bottom of the next. +The command to control vertical spacing is +.BD .vs . +For running text, it is usually best to set the vertical spacing +about 20% bigger than the character size. +For example, so far in this document, we have used +``9 on 11'', that is, +.P1 +^ps 9 +^vs 11p +.P2 +If we changed to +.P1 +^ps 9 +^vs 9p +.P2 +.vs 9p +.ne 3 +the running text would look like this. +After a few lines, you will agree it looks a little cramped. +The right vertical spacing is partly a matter of taste, depending on how +much text you want to squeeze into a given space, +and partly a matter of traditional printing style. +By default, +.UL troff +uses 10 on 12. +.PP +.vs 14p +.ps 12 +Point size and vertical spacing make a substantial difference in the amount of text +per square inch. +This is 12 on 14. +.ne 2 +.PP +.ne 2 +.ps 6 +.vs 7p +Point size and vertical spacing make a substantial difference in the amount of text +per square inch. +For example, +10 on 12 uses about twice as much space as 7 on 8. +This is 6 on 7, which is even smaller. +It packs a lot more words per line, +but you can go blind trying to read it. +.PP +When used without arguments, +.BD .ps +and +.BD .vs +revert to the previous size and vertical spacing +respectively. +.WS +.PP +The command +.BD .sp +is used to get extra vertical space. +Unadorned, +it gives you one extra blank line (one +.BD .vs , +whatever that has been set to). +Typically, that's more or less than you want, +so +.BD .sp +can be followed by +information about how much space you want _ +.P1 +^sp 2i +.P2 +means `two inches of vertical space'. +.P1 +^sp 2p +.P2 +means `two points of vertical space'; +and +.P1 +^sp 2 +.P2 +means `two vertical spaces' _ two of whatever +.BD .vs +is set to +(this can also be made explicit with +.BD .sp\ 2v ); +.UL troff +also understands decimal fractions in most places, +so +.P1 +^sp 1.5i +.P2 +is a space of 1.5 inches. +These same scale factors can be used after +.BD .vs +to define line spacing, and in fact after most commands +that deal with physical dimensions. +.PP +It should be noted that all size numbers are converted internally +to `machine units', which are 1/432 inch +(1/6 point). +For most purposes, this is enough resolution +that you don't have to worry about the accuracy of the representation. +The situation is not quite so good vertically, +where resolution is 1/144 inch +(1/2 point). |
