diff --git a/.hgtags b/.hgtags
--- a/.hgtags
+++ b/.hgtags
@@ -5,3 +5,4 @@ df8602459ab009cd967403f00f7aa13cecf368b8
 9b6820f9a10b631401b77cd849b2933b7a1c87c7 divide over explicit axis
 d811502e67f8799be24c751f305e92d223a4f3f5 divide over arbitrary axis
 9a4aa6470987b8147bd875bd9779eea3f6072727 rd coloring
+e730ce1f2d31ab502530c4e41706559b31493d5a rd fick laws