Added \indexsubitem definition; functions were previously indexed for the
wrong module.
diff --git a/Doc/lib/libbase64.tex b/Doc/lib/libbase64.tex
index ab00ded..edd1920 100644
--- a/Doc/lib/libbase64.tex
+++ b/Doc/lib/libbase64.tex
@@ -13,6 +13,8 @@
 \indexii{RFC}{1421}
 \index{MIME, base 64 encoding}
 
+\renewcommand{\indexsubitem}{(in module base64)}
+
 \begin{funcdesc}{decode}{input\, output}
 Decode the contents of the \var{input} file and write the resulting
 binary data to the \var{output} file.