Index: trunk/MagicSoft/Mars/mdata/MDataChain.cc
===================================================================
--- trunk/MagicSoft/Mars/mdata/MDataChain.cc	(revision 2927)
+++ trunk/MagicSoft/Mars/mdata/MDataChain.cc	(revision 2928)
@@ -39,5 +39,7 @@
 //   "HillasDource.fDist / (MHillas.fLength + MHillas.fWidth)"
 //
-// The allowed operations are: +, -, *, /
+// The allowed operations are: +, -, *, /, %
+//
+// While a%b returns the floating point reminder of a/b.
 //
 // Warning: There is no priority rule build in. So better use brackets