anchor.diff:             #:+hours-per-day+
              #:+days-per-week+
              #:+iso-8601-format+
  +           #:+rfc3339-format+
  +           #:+rfc3339-format/date-only+
              #:+asctime-format+
              #:+rfc-1123-format+
              #:astronomical-julian-date
  
positive.code:   '((:year 4) #\- (:month 2) #\- (:day 2) #\T
      (:hour 2) #\: (:min 2) #\: (:sec 2) #\.
      (:usec 6) :gmt-offset-or-z))
  (defparameter +asctime-format+
    '(:short-weekday #\space :short-month #\space (:day 2 #\space) #\space
      (:hour 2) #\: (:min 2) #\: (:sec 2) #\space
  
negative.code:                                   (timezone *default-timezone*))
    "Formats a timestring in the RFC 3339 format, a restricted form of the ISO-8601 timestring specification for Internet timestamps."
    (let ((rfc3339-format
           (if (and use-zulu
                    (not omit-date-part)
                    (not omit-time-part)
                    (not omit-timezone-part))
               +rfc3339-format+ ; micro optimization
               (append
                (unless omit-date-part
                  '((:year 4) #\-
                    (:month 2) #\-
                    (:day 2)))
                (unless (or omit-date-part
                            omit-time-part)
                  '(#\T))
                (unless omit-time-part
                  '((:hour 2) #\:
                    (:min 2) #\:
                    (:sec 2) #\.
                    (:usec 6)))
                (unless omit-timezone-part
                  (if use-zulu
                      '(:gmt-offset-or-z)
                      '(:gmt-offset)))))))
      (format-timestring destination timestamp :format rfc3339-format :timezone timezone)))
  
  (defun %read-timestring (stream char)
  