Are charge-backs/refunds out of scope?

[msporny]

Should charge-backs and refunds be handled outside of the API? Should the API only focus on initiating payments. It's true that a charge-back and refund could be viewed as a "reverse payment". However, we should be sure that we understand the ramifications of a charge-back/refund. For example, if the browser ends up holding digital receipts for items, would a charge-back/refund need to mark those digital receipts as invalid at that point? If so, we most likely need to spec that for interop.

It would be good to understand the use cases for charge-backs and refunds necessitating spec language (instead of saying it's out of scope for the spec).