diff --git a/Lib/fontTools/merge.py b/Lib/fontTools/merge.py
index fe61f94..a432a3c 100644
--- a/Lib/fontTools/merge.py
+++ b/Lib/fontTools/merge.py
@@ -260,6 +260,7 @@
 	'sTypoLineGap': max,
 	'usWinAscent': max,
 	'usWinDescent': max,
+	# Version 2,3,4
 	'ulCodePageRange1': onlyExisting(bitwise_or),
 	'ulCodePageRange2': onlyExisting(bitwise_or),
 	'usMaxContex': onlyExisting(max),