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+.\" Copyright (c) 1983, 1986, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"	This product includes software developed by the University of
+.\"	California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"	@(#)4.t	8.1 (Berkeley) 6/8/93
+.\"
+.nr H2 1
+.\".ds RH "Address representation
+.br
+.ne 2i
+.NH
+\s+2Internal address representation\s0
+.PP
+Common to all portions of the system are two data structures.
+These structures are used to represent
+addresses and various data objects.
+Addresses, internally are described by the \fIsockaddr\fP structure,
+.DS
+._f
+struct sockaddr {
+	short	sa_family;	/* data format identifier */
+	char	sa_data[14];	/* address */
+};
+.DE
+All addresses belong to one or more \fIaddress families\fP
+which define their format and interpretation.
+The \fIsa_family\fP field indicates the address family to which the address
+belongs, and the \fIsa_data\fP field contains the actual data value.
+The size of the data field, 14 bytes, was selected based on a study
+of current address formats.*
+Specific address formats use private structure definitions
+that define the format of the data field.
+The system interface supports larger address structures,
+although address-family-independent support facilities, for example routing
+and raw socket interfaces, provide only 14 bytes for address storage.
+Protocols that do not use those facilities (e.g, the current Unix domain)
+may use larger data areas.
+.FS
+* Later versions of the system may support variable length addresses.
+.FE