char-valid-p

char-valid-p is an alias for `characterp' in `mule.el'.

(char-valid-p OBJECT)

This function is obsolete since 23.1;
use `characterp' instead.

Return non-nil if OBJECT is a character.
In Emacs Lisp, characters are represented by character codes, which
are non-negative integers. The function `max-char' returns the
maximum character code.