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/libposix.tex b/Doc/lib/libposix.tex
index 593d7ca..aee6c0d 100644
--- a/Doc/lib/libposix.tex
+++ b/Doc/lib/libposix.tex
@@ -13,7 +13,7 @@
 
 \strong{Do not import this module directly.}  Instead, import the
 module \refmodule{os}, which provides a \emph{portable} version of this
-interface.  On \UNIX{}, the \refmodule{os} module provides a superset of
+interface.  On \UNIX, the \refmodule{os} module provides a superset of
 the \module{posix} interface.  On non-\UNIX{} operating systems the
 \module{posix} module is not available, but a subset is always
 available through the \refmodule{os} interface.  Once \refmodule{os} is