diff --git a/doc/htmlxref.cnf b/doc/htmlxref.cnf
new file mode 100644
index 000000000..13aa8ce45
--- /dev/null
+++ b/doc/htmlxref.cnf
@@ -0,0 +1,2 @@
+calc		mono	http://www.gnu.org/software/emacs/manual/html_mono/calc.html
+calc		node	http://www.gnu.org/software/emacs/manual/html_node/calc/