diff --git a/offlineimap.conf b/offlineimap.conf
index d3be8be..72a3fa8 100644
--- a/offlineimap.conf
+++ b/offlineimap.conf
@@ -327,10 +327,14 @@ remoteuser = username
 
 ########## Advanced settings
 
-# Some IMAP servers need a "reference" which often refers to the
-# "folder root".  This is most commonly needed with UW IMAP, where
-# you might need to specify the directory in which your mail is
-# stored.  Most users will not need this.
+# Some IMAP servers need a "reference" which often refers to the "folder
+# root".  This is most commonly needed with UW IMAP, where you might
+# need to specify the directory in which your mail is stored. The
+# 'reference' value will be prefixed to all folder paths refering to
+# that repository. E.g. accessing folder 'INBOX' with reference = Mail
+# will try to access Mail/INBOX. Note that the nametrans and
+# folderfilter functions will still apply the full path including the
+# reference prefix.  Most users will not need this.
 #
 # reference = Mail