So far I haven’t noticed much documentation on the exit statuses generated by Python itself (e.g. for unhandled exceptions). I did find some discussion in <https://docs.python.org/3/library/sys.html#sys.exit>, so perhaps I will add to that.

Since it implies values beyond 127 may not work on some systems, I now propose to use the arbitrary value of 120 instead of 255. (Keeping clear of 126 and 127, which have a special meaning in Posix shells.) Although, that statement about 0–127 was added in 1998 (bbe92932a005), so may not be relevant these days.