When is a cast not a cast?

[Doug Gwyn]

In article <406 at skye.ed.ac.uk> richard at aiai.UUCP (Richard Tobin) writes:
>>Addition of pointers is a meaningless operation.
>Not always.
>  t = p + q;

But you haven't told us what this means!
What properties does t hypothetically have?
What is its type hypothetically supposed to be?
What can one legally do with it?
(Apparently, subtracting r is legal?  What are the official criteria?)

Other postings have explained why we don't think a reasonable, consistent
model for this feature is possible.