Hi Michael,
A's letter (page 57)
If all you want is to define a reference that refers to the current
page, that's what \xrdef and \xref are for.
http://tug.org/eplain/doc/eplain.html#Page-references
I suspect you already know that and want to do something else, but I
can't tell from your description what the goal is ...
Best,
Karl