Advanced FileMaker Pro Formula

If your mail list contains a mixture of ZIP+4 and 5-digit ZIP codes you can use the following formula to print barcodes on both regardless of ZIP length:

Change the calculation in the  field called BARcode to  the following formula:

If (Length (ZIPcode) = 5,"!" & Left (ZIPcode,5) & CorrectionDigit & "!","!" & Left (ZIPcode,5) & Right (ZIPcode,4) & CorrectionDigit & "!")

Make sure you designate the result of this calculation as text.