Function: CLR-FLAG

Source

(defun clr-flag (value flag &optional (flag-system *current-flag-system*))
  (cond ((and (listp flag) (not (null flag))) ;; list of flags?
	 (clr-flag (clr-flag value (cdr flag) flag-system)
		   (car flag)
		   flag-system))
	 ((not (null flag)) ;;one flag itself
	  (logand value (lognot (flag-value flag flag-system))))
	 (t value)))