\subsection{Description}The date class provides a set of functions for manipulating dates.  It contains attributes representing year, month and day quantities and a time of day.  It also contains an internal calendar which stores, for a given year and type of calendar, such quantities as thenumber of days per month and per year.  Gregorian and no-leap year dates are currently supported.  Operations on calendars include setting and getting date atributes, copying dates, and incrementing and decrementing dates.