The function unicode-char-equal
returns true if the characters char1 and char2 are equal, and the function unicode-char-not-equal
returns true if the characters char1 and char2 are not equal. Both functions ignore case using Unicode rules specified by style.
The current implementation only supports one style of comparison:
Compares characters using the simple case folding rules in Unicode 6.3.0.
LispWorks User Guide and Reference Manual - 20 Sep 2017