turn lower-case characters into upper-case characters
Major Section:  ACL2-BUILT-INS

(Char-upcase x) is equal to #\A when x is #\a, #\B when x is #\b, ..., and #\Z when x is #\z, and is x for any other character.

The guard for char-upcase requires its argument to be a standard character (see standard-char-p).

Char-upcase is a Common Lisp function. See any Common Lisp documentation for more information.

To see the ACL2 definition of this function, see pf.