Hi Darrel,
I'm a bit confused by the idea that a "RESUME (label)" is like a GOSUB. From the following quote in the PBP manual, it sounds more like RESUME (label) acts like a GOTO:

When the RESUME statement is encountered at the end of the BASIC
interrupt handler, it sets the GIE bit to re-enable interrupts and returns to
where the program was before the interrupt occurred. If RESUME is
given a label to jump to, execution will continue at that location instead.
All previous return addresses will be lost in this case.
I've always used RESMUE with a label, as I want to RESUME at a known location in the code, and have never had any issues, even in large programs with lots of other sub-routines.

Any further info would be great. Thanks,

Arch