The programs of a service share some tuning characteristics. The term event is used to refer to a single TV program. An event is 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. An event can be a complete program or an episode of a program.
Events are the typical entities which EPGs list to present program schedule information.
The term component is used to refer to the constituents of an event. The audio and video of a TV program are obvious examples. In case of multilingual programs there are multiple audio components. In case of interactive programs the components are the application documents and the other data the applications are using. The term fragment is used to refer to a subpart of a component.