interval variable date Time variable An interval variable for which allowable values represent a point in time on a calendar, with a year, month, and day, and on a clock, with hours, minutes, and seconds. There is no true zero point because a zero value on the calendar or on the clock does not represent a reference point for which distance from zero can be used to compare values in relative multiples. The "zero point" may vary by culture (for the calendar or clock used) and by computer system (which may set an arbitrary zero point or epoch for calculations in the representation of date as a quantitative value). SEVCO Brian S. Alper, Joanne Dehnbostel, Harold Lehmann Philippe Rocca-Serra ready for release