I don't know if this will be of any help to you or not, but it might be the basis for figuring something out. It is pasted right out of Quattro Pro Help.

"You can enter a date or time in many formats, such as 04-04-98, 04/04/98, and 01:42:30 PM.
Quattro Pro stores all dates as serial integers so that it can calculate dates as values. The minimum serial integer is
-109,571, which equals January 1, 1600; the maximum is 474,816, which equals December 31, 3199. The serial number appears in the input line when you select the cell.
Serial numbers let you use date or time values in formulas. For example, subtracting 10/1/92 from 10/8/92 results in 7. Time is represented as decimal fractions, between 0.000 (for 00:00:00) and 0.99999 (for 23:59:59). Mixed numbers indicate the date and time: 2.5 represents January 1, 1900 at 12:00 noon.

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