I searched the archive and found only a couple of ancient messages that
discussed this, and then only in passing. There is no body test. One of
those messages suggested it was too expensive in general (which it may well
be); another that it was fodder for a future extension (which it also may
well be).
I'm particularly interested in what others think of the tradeoffs of end-user
usefulness vs added costs in performance and complexity of implementation.
As a user, I want this. As an implementor, I'm not sure. Comments?
-- John