universal-time — a universal time.

time-zone — a time zone.

second, minute, hour, date, month, year, day, daylight-p, zone — a decoded time.

Returns the decoded time represented by the given universal time.

If time-zone is not supplied, it defaults to the current time zone adjusted for daylight saving time. If time-zone is supplied, daylight saving time information is ignored. The daylight saving time flag is nil if time-zone is supplied.

 (decode-universal-time 0 0) → 0, 0, 0, 1, 1, 1900, 0, false, 0 

;; The next two examples assume Eastern Daylight Time. 
 (decode-universal-time 2414296800 5) → 0, 0, 1, 4, 7, 1976, 6, false, 5 
 (decode-universal-time 2414293200) → 0, 0, 1, 4, 7, 1976, 6, true, 5 

;; This example assumes that the time zone is Eastern Daylight Time 
;; (and that the time zone is constant throughout the example). 
 (let* ((here (nth 8 (multiple-value-list (get-decoded-time)))) ;Time zone 
        (recently (get-universal-time)) 
        (a (nthcdr 7 (multiple-value-list (decode-universal-time recently)))) 
        (b (nthcdr 7 (multiple-value-list (decode-universal-time recently here))))) 
   (list a b (equal a b))) → ((T 5) (NIL 5) NIL)

Implementation-dependent mechanisms for calculating when or if daylight savings time is in effect for any given session.

encode-universal-time, get-universal-time, Section 25.1.4 (Time)