diff --git a/mercurial/match.py b/mercurial/match.py
--- a/mercurial/match.py
+++ b/mercurial/match.py
@@ -119,7 +119,11 @@ class match(object):
         found/accessed, with an error message
         '''
         pass
+    # If this is set, it will be called when an explicitly listed directory is
+    # visited.
     explicitdir = None
+    # If this is set, it will be called when a directory discovered by recursive
+    # traversal is visited.
     traversedir = None
     def missing(self, f):
         pass