diff --git a/tools/python/stylesheet/cat_stat.py b/tools/python/stylesheet/cat_stat.py
index e7c593f58d..da1d9f8055 100755
--- a/tools/python/stylesheet/cat_stat.py
+++ b/tools/python/stylesheet/cat_stat.py
@@ -1,4 +1,10 @@
 #!/usr/bin/env python
+
+"""
+First lists tags used by Organic Maps
+Then, popular tags among selected keys (see find_popular_taginfo for list) which are not yet used by Organic Maps are listed
+"""
+
 import csv
 import drules_struct_pb2
 import os