You can insert into the coupon design even barcode images, which can be later read by a barcode reader to make their input easier. Barcode images are automatically generated by Post Affiliate Pro and each barcode matches a coupon id.
You can add barcodes to a coupon by editing the coupon Design and using the variable {$barcodeimage} :
Then you affiliates will be able to see and print barcodes in section with promotion materials:
Type of this barcode is Code 25 (Interleaved 2 of 5). You can find more information about it here: https://en.wikipedia.org/wiki/Interleaved_2_of_5