SCSI tape question

I've been playing around with some SCSI tape drives and noticed something peculiar--or not intuitive. Perhaps someone can explain it. I'm doing a READ_6 (6 byte CDB) with the fixed bit 0 and a 65KB buffer. So the sense data coming back returns the residual byte count, as it should with the ILI bit set in the sense key. So far, so good. Now, when I come to a filenark, I'm expecting that the filemark bit (bit 7) will be set in the sense key. It doesn't happen, the result just comes back as 0 bytes read and a normal (NO_SENSE) sense result. The additional sense code and sense qualifier bytes are also 0. Is this normal behavior? I'dve thought that the filemark bit would be set in every case of a filemark being read. My X3T9 documents don't mention this behavior, but maybe I missed something. --Chuck