CASEIGNOREDP

Normally, lower-case and upper-case letters are considered equal by EQUALP, BEFOREP, MEMBERP, etc. However, if a variable named CASEIGNOREDP exists and its value is not TRUE, then those predicates consider lower-case and upper-case letters to be distinct (that is, not equal).

MAKE "CASEIGNOREDP "FALSE
SHOW EQUALP "a "A
false

MAKE "CASEIGNOREDP "TRUE
SHOW EQUALP "a "A
true