|Microsoft DirectX 9.0|
System messages are not exclusive to any channel. There are three kinds, as shown in the following table.
|System common||Miscellaneous commands and data|
|System exclusive||Equipment-specific commands and data|
|System real-time||Synchronization of clock-based MIDI equipment|
Unlike other MIDI messages, system exclusive messages can contain any number of data bytes. After transmitting the data, the sequencer sends a system common message called an EOX, which signals the end of the system exclusive message.
In DirectMusic, the DMUS_SYSEX_PMSG structure contains the length of the data and a pointer to an array of data bytes.