anchor.diff:                           (princ #\Z str)
                            (format str "~c~2,'0d~c~2,'0d"
                                    (if (minusp offset) #\- #\+)
  -                                 (abs (floor offset 3600))
  +                                 (abs (floor offset +seconds-per-hour+))
                                    time-separator
  -                                 (abs (floor (mod offset 3600) 60))))))))))
  +                                 (abs (floor (mod offset +seconds-per-hour+)
  +                                             +seconds-per-minute+))))))))))
       (when destination
         (princ str destination))
       str))
  
positive.code:                              (timezone source (timezone-of source))))
               (offset-sign (signum offset-diff)))
          (multiple-value-bind (offset-day offset-sec)
              (floor (abs offset-diff) 86400)
            (let ((new-day (+ (day-of source) (* offset-sign offset-day)))
                  (new-sec (+ (sec-of source) (* offset-sign offset-sec))))
              (cond ((minusp new-sec)
                     (incf new-sec 86400)
                     (decf new-day))
                    ((>= new-sec 86400)
                     (incf new-day)
                     (decf new-sec 86400)))
              (cond
                (destination
                 (setf (nsec-of destination) (nsec-of source)
  
negative.code:                             (- year 2000)))
           (years-as-days (years-to-days internal-year))
           (zone (realize-timezone timezone))
           (sec (+ (* hour +seconds-per-hour+)
                   (* minute +seconds-per-minute+)
                   sec))
           (days-from-zero-point (+ years-as-days
                                    (aref #.+rotated-month-offsets-without-leap-day+ 0-based-rotated-month)
  