Ron Rosenfeld wrote in
:

Yeah, but there isn't any regulation allowing substitution of GPS for other
NAVAID's.

I think the AIM revision was just published today on the FAA web site. I
find it pretty confusing in terms of which units are allowed to do what.

But if the AIM is not regulatory, why does it matter?

IIRC, the Regs only say that you must have the equipment necessary for the
specific navigation being used.