Block layer discard requests

Poking around the latest ATA8-ACS and SCSI drafts I can find no sign of the ATA TRIM command
(in D1699r6-ATA8-ACS.pdf). Willy, could you give a document reference.

As for the SCSI PUNCH command that is in the Object Storage Devices (OSD-2) command set. No
wonder it is complex with a 236 byte cdb! Is OSD appropriate for flash devices? [Sledge hammer
for an acorn.] Surely a new SCSI command is needed in SBC-3 (SCSI Block Commands as used by
disks today) and the command name "TRIM" hasn't been used yet.

Also, there are the SCSI to ATA Translation (SAT) PASS-THROUGH commands that allow, for
example, a ATA TRIM command to be tunnelled through a SCSI command layer.