+This can also be a function designator; it is called without arguments
+ and should return a string.
+It can use `match-string' to get parts matched against
+`bug-reference-bug-regexp', specifically:
+ 1. issue kind (bug, patch, rfe &c)
+ 2. issue number.
+
+There is no default setting for this, it must be set per file.
+If you set it to a symbol in the file Local Variables section,
+you need to add a `bug-reference-url-format' property to it:
+\(put 'my-bug-reference-url-format 'bug-reference-url-format t)
+so that it is considered safe, see `enable-local-variables'.")