Formal compliance means that the software conforms to the criteria for implementation compliance and a formal proof exists that the following date operations anywhere in the software are equivalent to those in DateBench:
•determination of leap year
•conversion from a Gregorian date to day of the year
•conversion from day of the year to Gregorian date
•comparison of dates
•determination of the day of the week
•adding or subtracting days to a date
•subtracting a date from another date.