Markup fix.
diff --git a/Doc/lib/libmailbox.tex b/Doc/lib/libmailbox.tex
index 80ef40c..7c716b7 100644
--- a/Doc/lib/libmailbox.tex
+++ b/Doc/lib/libmailbox.tex
@@ -1285,13 +1285,13 @@
separated by any line that begins exactly with the string \code{'From
'} (note the trailing space) if preceded by exactly two newlines.
Because of the wide-range of variations in practice, nothing else on
-the From_ line should be considered. However, the current
+the \samp{From_} line should be considered. However, the current
implementation doesn't check for the leading two newlines. This is
usually fine for most applications.
The \class{UnixMailbox} class implements a more strict version of
-From_ line checking, using a regular expression that usually correctly
-matched From_ delimiters. It considers delimiter line to be separated
+\samp{From_} line checking, using a regular expression that usually correctly
+matched \samp{From_} delimiters. It considers delimiter line to be separated
by \samp{From \var{name} \var{time}} lines. For maximum portability,
use the \class{PortableUnixMailbox} class instead. This class is
identical to \class{UnixMailbox} except that individual messages are