A single file contains all information for a complete presentation. Each presentation file contains both data and software for the presentation. It includes both the data and software provided to the user and that retained by the server for the performance of the presentation. The basic building block for a presentation is a frame. The presentation file can contain a file header frame and multiple media frames, and one or more meta data frame. Of the frame types, the file header frame is the only one whose presence is mandatory in the presentation file format. The file header frame identifies the subject matter and contents of the presentation file providing information on the media types and total length of the file. The most degenerate yet useful version of a presentation file would have the file header frame followed by a media frame containing a thumbnail description. A thumbnail description may constitute a simple still picture or written description of the subject matter. Other media frames can be animated or full motion descriptions of the subject matter. Meta data frames are frames that contain non-media specific data file level behavior and user information. Meta data frames are presented only in cases where non-fault behavior and configuration are desired or in cases where actions and abstract navigational semantics are to be incorporated.
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