Re: What is the purpose of "To bind the key M-DEL, use "\M\d", not M-DEL"

[Richard Stallman]

    If you do

      (global-set-key [M-DEL] nil)

    you get the error in the subject line.

DEL is not a meaningful function key since function key symbols are
lower case.  So this has to be an error.

At the Lisp level it is better to teach Lisp programmers the correct
rules than to try to DWIM.