You can use FormCalc in the exit event of ono of your date fields to populate a numeric field with difference in years between both dates.
NumericField1.rawValue = Num2Date(Abs(Date2Num(Birthday.formattedValue, "M-D-YYYY") - Date2Num(FutureDate.formattedValue, "M-D-YYYY")), "Y")
Thank you radzmar, sadly I do not know where to enter the formula you suggested. I found a page that mentions FormCalc (Form Properties / Default tab under the File menu option). My novice skills are not up to this challenge apparently. ;- (
I changed the field to a text field with Optional user input. I’ll have to buy a book and read up. ;- )