HP-25 Subroutines possible?

[bshoring]

The HP-38C, like the HP-25, & the HP-12C does not offer subroutines. However, in simulators, it is possible. In the latest update of RPN-38 CX for iPhone, Willy Kunz added 4 levels of subroutines, as well as flags and ISG/DSE looping, and these can considerably shorten programs or allow far more complex programs than before. No labels are used, simply line addressing. It works quite well. He did the same with the programmable simulator for the HP-32E. If it can be done here, I would think it could be done with an HP-25 simulator.