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/libsys.tex b/Doc/lib/libsys.tex
index 895ba91..32eac0b 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -156,7 +156,7 @@
   the like.  Most systems require it to be in the range 0-127, and
   produce undefined results otherwise.  Some systems have a convention
   for assigning specific meanings to specific exit codes, but these
-  are generally underdeveloped; Unix programs generally use 2 for
+  are generally underdeveloped; \UNIX{} programs generally use 2 for
   command line syntax errors and 1 for all other kind of errors.  If
   another type of object is passed, \code{None} is equivalent to
   passing zero, and any other object is printed to \code{sys.stderr}