(case-fold-up-char ch #!optional (uc-list default-uppercase-list) (lc-list default-lowercase-list))
Returns the uppercase form of ch if ch is a member of lowercase-list, otherwise return ch.
The implied mapping from uppercase to lowercase in the two lists is one-to-one. The first element of the uppercase list is the uppercase form of the first element of the lowercase list, and vice versa.
The character to fold down.
The list of uppercase letters. The default is the list of English uppercase letters.
The list of lowercase letters. The default is the list of English lowercase letters.