Like the one we've used on bank cheques* for all of time

MICR E13-B: http://www.micr-fonts.com/MICRfont/micrfont.html

(*British. <grin>)

I meant one that could be created by hand, but that works for ones made by printer.

Or on snail mail.

Morse code, alpha bravo charlie, ASCII... there's actually a long history of doing this. Maybe not one meant for easy of memorization and drawing though. Even Mark Whatney had to be taught Morse code on Mars.

(Yes the phonetic alphabet is meant for ease of hearing by people, but writing a program to understand 26 distinct sounds can't be nearly as hard as natural language transcription.)