Anyone implemented this yet. I have font and understand the format have trouble creating calculation. Beyond my skill level frankly but I do a lot of mailing and its a good thing to have. trying not to recreate the wheel if possible. Other issue is what happen when zip is not 5+4?

You might want to check out the USPS rules:

http://www.usps.com/ncsc/addressservices/certprograms/barcode.htm

Also, Brian Dunning (who does great work) has some FileMaker stuff regarding this, here:

http://www.briandunning.com/bar-code/

-Stanley

I'm sure that can work and I have spent quite a bit time researching Postnet and have learned a lot. What I have learned is that it is difficult and expensive to do in Filemaker yet free and easier in Microsoft applications. Since what I am doing is creating some 2000 labels for a mailing I decided not to use Filemaker for this application. I keep it simple and export the database and mailmerge with MS Word and let it print the labels and Postnet barcode for me. Perhaps Filemaker will add this feature sometime in an update.