[PATCH] doc: detail inconsistencies in sed word boundary handling

* doc/autoconf.texi (Limitations of usual tools): Display a
table showing where the various syntaxes for word boundaries
are supported.
---
 doc/autoconf.texi | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 4be1f70..2e4b7ba 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -19666,6 +19666,18 @@ $ @kbd{echo abc | busybox sed '/a\(b\)c/ s/a\(b\)c/\1/'}
 b
 @end example
 
+Portable scripts should be aware of the inconsistencies and
+options for handling word boundaries.
+
+@example
+                \<      \b      [[:<:]]
+Solaris 10      yes     no      no
+Solaris XPG4    yes     no      error
+NetBSD 5.1      no      no      yes
+FreeBSD 9.1     no      no      yes
+GNU             yes     yes     error
+busybox         yes     yes     error
+@end example
 
 @item @command{sed} (@samp{t})
 @c ---------------------------
-- 
2.5.5