Verifies that an item evaluates to nil
Supported Platforms: Windows and Mac OS
(not item)
Type: Integer, Real, String, List, Subroutine, Ename (entity name), T, or nil
An AutoLISP expression.
Type: T or nil
T if item evaluates to nil; otherwise nil.
Typically, the null function is used for lists, and not is used for other data types along with some types of control functions.
(setq a 123 b "string" c nil) nil (not a) nil (not b) nil (not c) T (not '()) T