I'm curious, I hear this alot, but when I'm coding, whenever I need to type out constants, they're in ALL-CAPS. Do you remap caps-lock to an unused spot, or do you hold down shift while typing? I'm usually in vim or equivalent most of the time, FWIW.
I see it in Programmable Logic Controllers. Engineering drawings often come in all caps and a program's input and output buffers are sometimes named to match. The older programs were in all caps because the programming terminals had no lowercase.