For RPG-II Experts

We have RPG-II on our mainframe platform (no comments needed for
that) and I want to write a mainframe assembler subroutine to work with an
RPG-II main program and exchange information between the two.

I've read that the RPG RLABL opcode allows an external assembler
subroutine to gain addressability at compile-time to an area defined in
the calling RPG program. The RPG-II manual further identifies the fact
that the assembler program must code a V-type address constant to obtain
the compile-time address to the RPG area. That is pretty
straight-forward. However...

I further read that the RPG ULABL opcode allows an RPG program to
gain addressability at compile-time to an area defined in an external
assembler subroutine. But, what I have not found is how to define the
area in the assembler program so that the RPG program will receive an
address at compile-time to the appropriate area. Can anybody possibly
tell me the answer to that question?

Thanks.

Sincerely,

Dave Clark