[This is preliminary documentation and subject to change.]
The Program Guide can obtain program data from various suppliers and in various formats. A satellite service provider may supply Program Guide data over one of the provided satellite channels. A local cable operator may supply Program Guide data through a vendor that sells subscriptions to such data downloaded from the Internet nightly. Satellite broadcast schedules may arrive as data packets from the satellite, and cable TV program data may arrive as a downloaded file or data transmitted over the vertical blanking interval (VBI) in the analog television signal.
The following illustration shows some of the various possible data sources feeding the Guide database.