char-lessp char-greaterp char-not-lessp char-not-greaterp char-not-equal

(char-lessp character &rest characters) -- (char-greaterp character &rest characters) -- (char-not-lessp character &rest characters) -- (char-not-greaterp character &rest characters) -- (char-not-equal character &rest characters)

The case-INSENSITIVE character ordering family, the counterparts of char< / char> / char>= / char<= / char/=: each argument is downcased before its code point is compared. char-lessp is true when the arguments are in strictly increasing order, char-greaterp in strictly decreasing order, char-not-lessp in non-increasing order, char-not-greaterp in non-decreasing order, and char-not-equal when ALL arguments are pairwise distinct.