[gumby]

> So, it’s a de-facto standard that boils down to mostly “what did 4.2BSD understand?“

By the way 4.2BSD was being compatible with older or contemporary implementations, like ITS which was running TCP before any Unix was.

For example plenty of machines back then used octal as a preferred human representation. In fact that’s why octal is the default format of numeric constants in C: C, like Unix, was initially developed for an 18-bit (six octal digits) PDP-7. The smaller 16-bit PDP-11 version came later.