The DCDM is a set of uncompressed and unencrypted files that represent moving image content optimized for the electronic playback in theaters. The specification embraces not only theatrical feature films but is also intended for content like trailers and advertisements; the full range of works are called compositions in the specification. The DCDM's files or tracks contain images (high resolution representations of motion picture frames, often produced by scanning film), audio, subpictures and/or timed text (mainly subtitles and/or captions), and auxiliary data (which includes such things as data to control room lights and curtains in a theater). A Composition Playlist synchronizes the playback of these files.