[exim-dev] calling an ACL from an expansion

In a fit of coding insanity I ran up the following:

+ 9. New expansion item ${acl {name}{argument}} to call an ACL.  The argument can
+    be accessed by the ACL in $address_data.  The expansion result is set by
+    a "message =" modifier and an "accept" return from the ACL.

Is there any value in this going forward?
--
Jeremy