Date:  May 05, 1993                      X3T9.2/93-037 rev 2


         To:  X3T9.2 Committee (SCSI)

         From:  George Penokie (IBM)

         Subject:  When to issue SDTR after WDTR

         It not 100% clear in SCSI-2 that anytime a WDTR message is
      |  accepted that it must be followed immediately by a SDTR
         message.

         I propose that in the SCSI-3 SIP document the following be
         added to make it clear that a SDTR message must follow a WDTR
         message that has not been rejected:

         In the section which describes the WDTR message the following
         should be added:

         If an SCSI device implements both wide data transfer option
         and synchronous data transfer option, then it shall negotiate
         the wide data transfer prior to negotiating the synchronous
         data transfer agreement.  If a synchronous data transfer
      |  agreement is in effect, then an SCSI device that does not
      |  reject, with a MESSAGE REJECT Message, a WDTR message shall
      |  reset the synchronous agreement to asynchronous mode.  If a
      |  WDTR message is rejected the prior synchronous data transfer
      |  agreement shall remain intact.