diff --git a/hgext/keyword.py b/hgext/keyword.py
--- a/hgext/keyword.py
+++ b/hgext/keyword.py
@@ -110,12 +110,20 @@ colortable = {
 
 # date like in cvs' $Date
 def utcdate(text):
+    ''':utcdate: Date. Returns a UTC-date in this format: "2009/08/18 11:00:13".
+    '''
     return util.datestr((text[0], 0), '%Y/%m/%d %H:%M:%S')
 # date like in svn's $Date
 def svnisodate(text):
+    ''':svnisodate: Date. Returns a date in this format: "2009-08-18 13:00:13
+    +0200 (Tue, 18 Aug 2009)".
+    '''
     return util.datestr(text, '%Y-%m-%d %H:%M:%S %1%2 (%a, %d %b %Y)')
 # date like in svn's $Id
 def svnutcdate(text):
+    ''':svnutcdate: Date. Returns a UTC-date in this format: "2009-08-18
+    11:00:13Z".
+    '''
     return util.datestr((text[0], 0), '%Y-%m-%d %H:%M:%SZ')
 
 # make keyword tools accessible