Binary running from DOS 3.3 or ProDOS

TechCowboy

New Tinkerer
Oct 31, 2021
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I'm writing a binary that adds ampersand routines to Applesoft BASIC.
If I'm running from DOS 3.3, I need to JMP DOSWARM to exit, but if I use ProDOS I can just RTS.

Question:
What is the recommended way to detect what DOS is running programmactically?