This function takes leap years into account, and is to that extent affected by the changeover date for the Gregorian calendar as specified in Preferences; but it does not allow for the 10 or 11 days that were deducted from the calendar, owing to the changeover date for the Gregorian calendar, when adding or subtracting months and days.
Timespan in years (positive for later and negative for earlier). Defaults to 0 if not supplied.
Timespan in months (positive for later and negative for earlier). Defaults to 0 if not supplied.
Timespan in days (positive for later and negative for earlier). Defaults to 0 if not supplied.
=CalcDate(%INDI.BIRT.DATE%, 0, -10)