[Techtalk] a and d characters

[Hamster]

Hi,

Today I learnt what a-characters and d-character are. I'm wondering if "a"
and "d" comprise the full set though. Are there "b" and "c" characters? How
about "e"?

Hoping someone might be able to shed some light on this :)

Hamster

PS - for the curious, a-characters are in the set:

A-Z 0-9 !"%&'()*+,-./:;<=>?_.  (spaces too)

d-characters are:

A-Z 0-9 - (no spaces)