(correct me if I am wrong). Most fixed hard drives have a lun of 0, but drives with multiple media (like a multi card reader) have multple luns with one id, so the CD changer is "probably" lun 0-5. Otherwise you would quickly run out of Scsi IDs which is not the case with may readers.
No need to correct, you are right.
Source: I own multiple SCSI card readers.
