--- a/contrib/purge/purge.py
+++ b/contrib/purge/purge.py
@@ -3,6 +3,16 @@
# This is a small extension for Mercurial (http://www.selenic.com/mercurial)
# that removes files not known to mercurial
#
+# This program was inspired by the "cvspurge" script contained in CVS utilities
+# (http://www.red-bean.com/cvsutils/).
+#
+# To enable the "purge" extension put these lines in your ~/.hgrc:
+# [extensions]
+# purge = /path/to/purge.py
+#
+# For help on the usage of "hg purge" use:
+# hg help purge
+#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or