These functions perform calendrical computations using time values
(the kind of list that
This returns the time difference t1 − t2 between two time values, in the same format as a time value.
This returns the sum of two time values, one of which ought to represent a time difference rather than a point in time. Here is how to add a number of seconds to a time value:(time-add time (seconds-to-time seconds))
This function returns the number of days between the beginning of year 1 and time.
This returns the day number within the year corresponding to time.