DA does the reverse. Unit used to connect various parts of a MIDI system, such as computers, keyboards, sound modules, synch units, etc. Type 0 files have all data on ONE time ordered track. Type 1 have multiple tracks. Type 2 are pattern files.
Sequencers can be dedicated hardware units or computer software.
Society of Motion Picture and Television Engineers format for synchronization of video and audio. Several subformats exist. Connected one to a set of powered speakers or a stereo, and you can record and playback both MIDI and audio. Usually also has a keyboard attached. System Exclusive events are specific to each hardware manufacturer.