anchor.diff:  (defun modified-julian-date (local-time)
     (- (day-of local-time) +modified-julian-date-offset+))
   
  -(defun local-time-diff (time-a time-b)
  -  "Returns a new LOCAL-TIME containing the difference between TIME-A and TIME-B"
  +(defun encode-duration (&key (nsec 0) (usec 0) (msec 0) (sec 0) (minute 0) (hour 0) (day 0) (week 0))
  +  (+ (* +seconds-per-minute+
  +        (+ (* +minutes-per-hour+
  +              (+ (* +hours-per-day+
  +                    (+ (* +days-per-week+
  +                          week)
  +                       day))
  +                 hour))
  +           minute))
  +     sec
  +     (/ (+ (/ (+ (/ nsec
  +                    1000)
  +                 usec)
  +              1000)
  +           msec)
  +        1000)))
  +
  +(defun local-time- (time-a time-b)
  +  "Returns the difference between TIME-A and TIME-B in seconds"
     (multiple-value-bind (day-a sec-a)
         (local-time-adjust time-a (timezone-of time-b))
  -      (let ((nsec (- (nsec-of time-a) (nsec-of time-b)))
  -            (seconds (- sec-a (sec-of time-b)))
  -            (days (- day-a (day-of time-b))))
  -        (when (minusp nsec)
  -          (decf seconds)
  -          (incf nsec 1000000000))
  -        (when (minusp seconds)
  -          (decf days)
  -          (incf seconds 86400))
  -        (make-local-time :nsec nsec
  -                         :sec seconds
  -                         :day days))))
  +    (let ((nsec (- (nsec-of time-a) (nsec-of time-b)))
  +          (second (- sec-a (sec-of time-b)))
  +          (day (- day-a (day-of time-b))))
  +      (when (minusp nsec)
  +        (decf second)
  +        (incf nsec 1000000000))
  +      (when (minusp second)
  +        (decf day)
  +        (incf second 86400))
  +      (encode-duration :nsec nsec :sec second :day day))))
  +
  +(defun local-time+ (time seconds)
  +  "Returns a new LOCAL-TIME containing summing TIME and SECONDS"
  +  (adjusted-local-time :sec seconds time))
   
   (defun local-time-sum (time-a time-b)
     "Returns a new LOCAL-TIME containing the sum of TIME-A and TIME-B"
  
positive.code: (defconstant +minutes-per-hour+ 60)
  
  (defconstant +hours-per-day+ 24)
  
  (defconstant +leap-factor+ 1461)
  
  
negative.code:            #:+minutes-per-day+
             #:+minutes-per-hour+
             #:+hours-per-day+
             #:+days-per-week+
             #:astronomical-julian-date
             #:modified-julian-date
             #:astronomical-modified-julian-date))
  