Getting the Default Form Object
You must get the form object from the custom plug-in using getEPForm.
var epPaymentSelectionForm = epPlugin.getEPForm(); setPaymentType(pTypeParam);// Setting the Payment Type using setPaymentType method
"DD" = Invoice Payment Processing Form
Note:
The error EP_API_PAYMENTTYPE_INVALID is displayed if the payment type is invalid. The supported payment type is DD.