Requirements related to the Global usage case are listed. In this document TV Broadcast is used as the generic term to refer to currently existing TV systems, their transport protocols, and their typical operation of content provision and distribution. The term TV Broadcast URI refers to URIs which identify, and possibly locate, TV Broadcast content. Typically, TV Broadcast systems are push systems. Hierarchy in TV Broadcast content TV Broadcast content is modeled in a four-layer hierachy, consisting of service, event, component, and fragment.
Service is at the top, fragment is at the bottom of the hierarchy.
The term service is used to refer to a concatenation of programs, all being broadcast by the same service provider. The programs of a service share some tuning characteristics. The term event is used to refer to a single TV program. An event consumes a time period within a service and therefore can be characterized with begin and end times. The service provider determines the granularity in which the service is split in events.