According to the API documentation, once a credit card number is read, the client will generate a token and this is passed to the source_id field in CreatePayment.
I see in API Explorer that for the field source_id, there is a drop down list box where you can select card OK status or even card declined. Doesn’t this mean that by the time I get to calling CreatePayment, I will already be able to tell if a card was declined already based on the source_id?