A TV receiver such as a set-top box has an Open Cable Application Platform (OCAP) programming interface that communicates with interactive digital video applications such as pay-per-view applications to enable a viewer to communicate requests, purchase orders, and the like to a head end. A cable card provides both decryption of incoming video from the head end as well as translation functionality that transforms standardized messages into a proprietary protocol recognizable to the head end. The OCAP has an API that interfaces with the application and that directs standardized messages from the application to the standardized interface of the removable cable card ensuring common reliance on the translation functionality built in to the cable card.