| Rule: | GetNumPlayingTracksNotSentBeforeGetPBTrackInfo |
| Version: | ATS 4.1 |
| Description: | Fire an error if GetPBTrackInfo is sent and GetNumPlayingTracks has not been sent previously. |
| Specification: | N/A |
| Error: | accessory did not check the number of tracks in playback engine before calling GetPBTrackInfo |