An interesting fact is that most Z-machine interpreters provide a setting for the interpreter version (header address 1F, in the form of an upper-case letter) along with setting the interpreter number (1. DECSystem-20, 2. Apple IIe, and so on,) but unlike the number, I haven’t been able to find any information on what the version letter does.
Which games check it and what do they do with it? Is it a useful setting, and if so, what default value should it have?
EDIT: The tool tip in Zoom says “Most games just report this at the start and make no further use of it,” which I take to mean that it has no known effect other than this.