-# :vcs_info:<vcs-string>
-# ...where <vcs-string> is one of: git, hg, bzr, svn or svk
+# :vcs_info:<user-context>:<vcs-string>
+# ...where <vcs-string> is one of:
+# - git, git-svn, hg, darcs, bzr, mtn, svn, cvs or svk
+# ...and <user-context> is a freely configurable string, assignable
+# by the user as the first argument to vcs_info().
+#
+# There is one special value for <vcs-string> named 'init', that
+# is in effect as long as there was no decision what vcs backend to use.
+#
+# There are two pre-defined values for <user-context>:
+# default - the one used if none is specified
+# command - used by vcs_info_lastmsg to lookup its styles.
+# You may *not* use 'print_systems_' as a user-context string,
+# because it is used internally.