anchor.diff:                   (* minute +seconds-per-minute+)
                    sec))
            (days-from-zero-point (+ years-as-days
  -                                  (aref #.+rotated-month-offsets-without-leap-day+ 0-based-rotated-month)
  +                                  (aref +rotated-month-offsets-without-leap-day+ 0-based-rotated-month)
                                     (1- day))))
       (multiple-value-bind (utc-sec utc-day)
           (%adjust-to-offset sec days-from-zero-point (- offset))
  
positive.code:     (let* ((leap-day-p (= remaining-days 365))
             (rotated-1-based-month (if leap-day-p
                                        12 ; march is the first month and february is the last
                                        (position remaining-days #.+rotated-month-offsets-without-leap-day+ :test #'<)))
             (1-based-month (if (>= rotated-1-based-month 11)
                                (- rotated-1-based-month 10)
                                (+ rotated-1-based-month 2)))
             (1-based-day (if leap-day-p
                              29
                              (1+ (- remaining-days (aref #.+rotated-month-offsets-without-leap-day+
                                                          (1- rotated-1-based-month)))))))
        (values
         (+ years
  
negative.code:            (day (day-of time)))
         (case part
           (:nsec (setf nsec (coerce new-value '(integer 0 999999999))))
           (:sec-of-day (setf sec (coerce new-value `(integer 0 ,+seconds-per-day+))))
           (:day (setf day new-value)))
         (values nsec sec day)))
      (otherwise
  