from ginsbach@netbsd, -r1.18:

Document that getopt_long(3) can and will accept unique abbreviated long
option names.  This feature has been present since getopt_long(3) was first
released in NetBSD 1.5.  This is also standard GNU getopt_long(3) behavior.
ok millert

src/lib/libc/stdlib/getopt_long.3

@@ -1,4 +1,4 @@
-.\"	$OpenBSD: getopt_long.3,v 1.14 2007/05/31 19:19:31 jmc Exp $
+.\"	$OpenBSD: getopt_long.3,v 1.15 2007/07/03 12:06:07 jmc Exp $
 .\"	$NetBSD: getopt_long.3,v 1.11 2002/10/02 10:54:19 wiz Exp $
 .\"
 .\" Copyright (c) 1988, 1991, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"     @(#)getopt.3	8.5 (Berkeley) 4/27/95
 .\"
-.Dd $Mdocdate: May 31 2007 $
+.Dd $Mdocdate: July 3 2007 $
 .Dt GETOPT_LONG 3
 .Os
 .Sh NAME
@@ -93,6 +93,11 @@ It is possible to combine these methods, providing for long options
 processing with short option equivalents for some options.
 Less frequently used options would be processed as long options only.
 .Pp
+Abbreviated long option names are accepted when
+.Fn getopt_long
+processes long options if the abbreviation is unique.
+An exact match is always preferred for a defined long option.
+.Pp
 The
 .Fn getopt_long
 call requires a structure to be initialized describing the long