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At a first glance, card processing might encapsulate the business logic that is specified inside “L2” specifications. However, payment networks have different view on this level of abstraction. So, it is impossible to rely on such definition. For example, “exception file list management” is an on option part of some contactless “L2” ICS but it is a feature that is typically dependent on acquirer/processor context.
Hence, it would be more accurate to define the card processing as being the business logic that is stable whatever the merchant environment that will integrate it. Stability of the Level 2