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.FUNCTION....: V - Date Validation
.CATEGORY....: functions
The date validation function is "V". It can be used by specify that the function is to be validation: "/Fv".

If the date specified on the /A parm is valid, produces "" (the null string). Otherwise, produces "ERROR" and a non-zero errorlevel by triggering Fdate's error-handling function. (See the section on Fdate's ERROR HANDLING, later in this documentation.)

When using the /Fv parameter, you will almost always want to check success of the date validation by checking the errorlevel, and to redirect Fdate's output to NUL (so that when it writes the null string, it does not produce a blank line on your screen).

When processing an input date, Fdate does not reject all invalid dates: specifically, it is very forgiving about the number in the day- of-the-month part of input dates. It will accept, for example, 19931144 (November 44, 1993 in CCYYMMDD format) and process it quite happily (as December 14, 1993). This is not a bug, it is a feature. This feature provides one way (admittedly a crude one) of doing date arithmetic. The date part (JJJ) of a Business Julian input date can be used in the same way.

This feature can be a drawback, however, if you want to be sure that some date (say a date that a user entered as an input parameter) is valid. The /Fv function provides a way of completely checking a date for validity. It will, for example, reject November 44, 1993 as invalid.