(slib.info)Time and Date

If `(provided? 'current-time)':

The procedures `current-time', `difftime', and `offset-time' deal with
a "calendar time" datatype which may or may not be disjoint from other
Scheme datatypes.

 - Function: current-time
     Returns the time since 00:00:00 GMT, January 1, 1970, measured in
     seconds.  Note that the reference time is different from the
     reference time for `get-universal-time' in Note: Common-Lisp
     Time.

 - Function: difftime caltime1 caltime0
     Returns the difference (number of seconds) between twe calendar
     times: CALTIME1 - CALTIME0.  CALTIME0 may also be a number.

 - Function: offset-time caltime offset
     Returns the calendar time of CALTIME offset by OFFSET number of
     seconds `(+ caltime offset)'.