## Storage Device Driver Reference

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### READ SUB-CHANNEL (42h)

The READ SUB-CHANNEL command requests that the target return the requested sub-channel data plus the state of audio play operations.

Note: If a READ SUB CHANNEL command is issued to request the media catalog number (UPC/EAN Bar Coding), the drive should return the UPC code in ASCII format as specified in the SCSI-2 specification. Some drives return the UPC code in BCD. It should be converted to ASCII prior to returning. All other sub-channel data is returned in binary format.

Refer to the ANSI SCSI-2 specification for a detailed description of this command.