Question about the Ignore Wide Residue message

[shiang at corp.cirrus.com]

     Gentlemen:
     
     I have a question about the Ignore Wide Residue message. The SCSI 2 
     spec (X3T9.2 375R revision 10K) states that the Ignore Wide Residue 
     shall be sent immediately following that DATA IN phase and prior to 
     any other message. 
     
     The questions are :
     1. Why does this message only apply to the target side of a SCSI bus. 
     The target sends this message to the initiator, but the initiator does 
     not send this message to the target. 
     Also, is it necessary for a target to send this message when the DATA 
     IN is a read command, since the initiator already knows that the block 
     length is not a multiple of the scsi width? 
     
     2. In what commands does the target send this message to the 
     initiator?  
     
     
     
     Shiang