The 'lower-case-p' predicate function checks if the 'char' expression is a lower case character. If 'char' is lower case a T is returned, otherwise a NIL is returned. Lower case characters are 'a' [ASCII decimal value 97] through 'z' [ASCII decimal value 122].
(lower-case-p #\a) ; returns T (lower-case-p #\A) ; returns NIL (lower-case-p #\1) ; returns NIL (lower-case-p #\[) ; returns NIL
See the
lower-case-p
predicate function form in the