These functions perform calendrical computations using time values (see Time of Day).
t if time value t1 is less than time value
This returns the time difference t1 - t2 between two time values, as a time value.
This returns the sum of two time values, as a time value. One argument should 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)
This function returns the number of days between the beginning of year 1 and time-value.
This returns the day number within the year corresponding to time-value.
This function returns
t if year is a leap year.