What is e in the cde triangle?

This is a terminology question.

The cde triangle in the title referes to the one in the modular representation theory of finite groups.

I understand that "c" is for "Cartan" and "d" is for "decomposition", but is there a good meaning of "e" (except for the letter order in English)?

• I don't think I've heard of a clever name for it. Is it just the next letter after $c$ and $d$? – anomaly Jun 14 '17 at 1:02