SteveT:
...
> The one thing I think MSDOS and CPM (and I think RT-11 too) got right
> is to use an extension for binary executables.
...

Then you might like VMS which had version numbers like FILE.TXT;3
https://docs.vmssoftware.com/guide-to-openvms-file-applications/#FILE_SPECS
Seem to still be very much alive:
https://vmssoftware.com/about/v921/

Regards,
/Karl Hammar