Program [EtherGuide Glossary]
For viewers and listeners of electronic media, a "program" or program serviceis something that one watches, with a start time, an end time, a duration and maybe even a title or selections within the "program."
A "digital program" on the other hand, is a linear service that provides, for a certain length of time, one or more audio-visual events.
An MPEG-2 program stream, by definition, carries one program. An MPEG-2 transport stream can carry one (a single program transport stream) or more (a multiple program transport stream) independent or associated programs.