The following fields are required: - sku= field, which is the album's sku code - amount= field, which is how much is being paid for this album in US Dollars - cc= field, which is a Credit card number (VISA/MASTERCARD only) OR gc= field, which is a gift card number (in which case the 'yy' and 'mm' fields are not needed) - yy= field, which is a two digit year of the credit card expiration date (zero padded) - mm= field, which is a two digit month of the credit card expiration date (zero padded) - name= field, which is the name of the buyer (if you want it to be blank, send "name=") - email= field, which is the email address of the buyer, so they can retrieve their purchases later if they lose the download info (if you want it to be blank, send "email=") - id= field, which is your partner id. Contact john@magnatune.com to obtain one. Sample URL: http://magnatune.com/buy/buy_dl_cc_xml?cc=4111312111111111&mm=12&yy=04&sku=phillips-trad&name=john&email=john@poopah.com&id=nik&amount=6