The PaymentRequest API requires that merchants supply a list identifiers for supported payment methods. This document defines those identifier strings and how they are created.
This is very rought draft intended to spark discussion.
One of the principles of the PaymentRequest API is that merchants must know how to accept payments from the payment methods that they claim to support. This allows the API to abstract away the details of specific payment methods and to add new ones over time without changing the API specification.
As part of the paymentRequest() call, the web page provides an array of strings that identify the supported payment methods. This document defines those strings.
Should the format of the identifiers be URLs (e.g. http://example.com/paymentmethod) or reverse host name (e.g. com.example.paymentmethod) or some other extensible syntax?
Should there be well-known identifiers that are simple strings defined in the spec that don't conform to the distributed extensbility syntax that are used for common payment methods?
A registration mechanism may exist to install the code for new payment methods into the user agent. This process would add support for a new payment method to the user agent. This mechanism should be defined in a separate specification.
If the identifier is a URL, should there be a resource that can be fetched from the URL
Is there a need to describe the payment method at the URL or provide some other information?
The Payment Method Identifier is a string that uniquely identifies a payment method that a user can use to complete a transaction. For example, Visa, MasterCard, and American Express are payment methods used in some countries.