>I am writing a business application and part of it is to produce a purchase order with the vendors part numbers barcoded. I understand that code 39 or 3 of 9 would be a good standard. I am wondering if this purchase order is faxed to the vendor will the bar code be still of a good enough quality for the wand scanner to work properly. is there a font set available that would be better for my application ?

Very likely not, unless you make the barcode very large. The limit of fax resolution is ~200dpi, little error correction/detection is implemented. You need to negotiate formatting and compliance testing with the vendor carefully, and I'd add extra characters to checksum the data value to aid in error detection. Some part # standards, like book ISBNs/ISSNs, have a check digit in them to do just that.

> another question I have is, should I add a "+" to the end of the part number so the wand scanner sends a carrage return to the computer after the part number is scanned?

That's part of the negotiation between you and the recipient.