Do the right magic to make \ABC{} get sorted correctly in the index.
diff --git a/Doc/lib/libtypes.tex b/Doc/lib/libtypes.tex
index dfe1ecb..33d1b15 100644
--- a/Doc/lib/libtypes.tex
+++ b/Doc/lib/libtypes.tex
@@ -118,7 +118,7 @@
\item[(1)]
\code{<>} and \code{!=} are alternate spellings for the same operator.
(I couldn't choose between \ABC{} and \C{}! :-)
-\indexii{\ABC{}}{language}
+\indexii{ABC@\ABC{}}{language}
\indexii{\C{}}{language}
\end{description}
diff --git a/Doc/libtypes.tex b/Doc/libtypes.tex
index dfe1ecb..33d1b15 100644
--- a/Doc/libtypes.tex
+++ b/Doc/libtypes.tex
@@ -118,7 +118,7 @@
\item[(1)]
\code{<>} and \code{!=} are alternate spellings for the same operator.
(I couldn't choose between \ABC{} and \C{}! :-)
-\indexii{\ABC{}}{language}
+\indexii{ABC@\ABC{}}{language}
\indexii{\C{}}{language}
\end{description}