Clean up some markup cruft.  A number of the macros that take no
parameters (like \UNIX) are commonly entered using an empty group to
separate the markup from a following inter-word space; this is not
needed when the next character is punctuation, or the markup is the
last thing in the enclosing group.  These cases were marked
inconsistently; the empty group is now *only* used when needed.
diff --git a/Doc/lib/libthread.tex b/Doc/lib/libthread.tex
index a2e5b7e..328e9b7 100644
--- a/Doc/lib/libthread.tex
+++ b/Doc/lib/libthread.tex
@@ -19,7 +19,7 @@
 IRIX, Solaris 2.x, as well as on systems that have a \POSIX{} thread
 (a.k.a. ``pthread'') implementation.
 \index{pthreads}
-\indexii{threads}{\POSIX{}}
+\indexii{threads}{\POSIX}
 
 It defines the following constant and functions: