Method for reformation conventional three field date formats to produce a century accumulated date

The present invention relates to a method for reformatting and using the existing 2 digit month field and the existing 2 digit day field in a conventional 8, 7 or 6 digit date format to accommodate new century information. The invention is particularly useful for dealing with 6 digits formats used in existing databases, for example, ASCII date formats of the form mm/dd/yy or dd/mm/yy or yy/mm/dd. The method of the present invention for encoding century information is based on numerically offsetting the range of 1 through 31 days in the day field and/or offsetting the range of 1 through 12 months in the month field. In ASCII, the constraint is the value of the largest number that can be represented in 2 digit ASCII form (i.e. 99). There can be 3 day field ranges, 1-31, 32-62, 63-93 within the range 1 through 99, and there can be 8 month field ranges, 1-12, 13-24, 25-36, 37-48, 49-60, 61-72, 73-84, 85-96. Each of the embodiments manipulate the digits in these fields to produce a century accumulated date. Thus, century may be inserted into the day field, the month field, or both the day and the month field. The century can also be extracted from the century accumulated date to produce a conventional date format.