MCI devices can have additional commands or extend the definition of the required and basic commands. While some extended commands only apply to a specific device driver, most of them apply to all devices of a particular type. For example, the MIDI sequencer command set extends the set command to add time formats that are needed by MIDI sequencers. You can find descriptions of extended commands in the command tables in this chapter. You can find a summary of the syntax used for the commands strings in Appendix A, “MCI Command String Syntax Summary.”