Remove all uses of \sectcode; we can now use logical markup everywhere.
diff --git a/Doc/libmailbox.tex b/Doc/libmailbox.tex
index e9dcb89..4ff2dedb 100644
--- a/Doc/libmailbox.tex
+++ b/Doc/libmailbox.tex
@@ -1,4 +1,4 @@
-\section{Standard Module \sectcode{mailbox}}
+\section{Standard Module \module{mailbox}}
 \label{module-mailbox}
 \stmodindex{mailbox}