--- a/mercurial/help/config.txt	Fri Aug 15 04:37:46 2014 +0200
+++ b/mercurial/help/config.txt	Fri Aug 15 23:05:53 2014 +0900
@@ -420,6 +420,10 @@
 only for :hg:`tag --remove`, but ``changeset.tag`` customizes the
 commit message for :hg:`tag` regardless of ``--remove`` option.
 
+At the external editor invocation for committing, corresponding
+dot-separated list of names without ``changeset.`` prefix
+(e.g. ``commit.normal``) is in ``HGEDITFORM`` environment variable.
+
 In this section, items other than ``changeset`` can be referred from
 others. For example, the configuration to list committed files up
 below can be referred as ``{listupfiles}``::