| MIDIERR_NOTREADY | MIDI output hardware is busy. |
| MIDIERR_STILLPLAYING | Driver is still playing MIDI data. |
| MIDIERR_UNPREPARED | MIDI data block has not been prepared. |
| WAVERR_BADFORMAT | Unsupported waveform data format. |
| WAVERR_STILLPLAYING | Driver is still playing waveform data. |
| WAVERR_UNPREPARED | Specified waveform data block has not been prepared. |