SAS Transport layer- ST_IFR/ST_ITS State machines

[Mona]

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Hello !! 
Could anybody please clear my doubts in SAS transport layer!!
<>I have some doubts . I am referring SAS Revision 3a, released on 22 April
2006
<>Following are the queries :
1.In the ST_IFR state machine it has been stated on page 383(section
9.2.6.2.2.2)that 
"If the ST_ITS state machine for the tag specified in the Send Task
Management Request is currently in use,then this state machine shall set
the retransmit bit argument to one. If the ST_ITS state machine for the
tag specified in the Send Task Management Request is not currently in
use, then this state machine shall set the Retransmit Bit argument to
zero."
I am not able to figure out which scenario is being talked out here. As per
my understanding, ST_ITS state-machine is busy when 
ST_IFR assigns it any task. After ST_ITS state machine sends Transmission
status(nak or ack/nak time-out etc) to ST_IFR state machine,
the ST_ITS state machine corresponding to that tag becomes free. Moreover, Is
there any static binding b/w ST_ITS state machine and TAG,
or that ST_IFR can allocate any state-machine when TASK/COMMAND request
arrives? I am concerned if I have missed something. 
2.Is CDB field's contents are visible to transport layer?
If no then how does Transport layer comes to know whether the COMMAND is a
read command or write command.
If Yes, then why does data size need to be specified exclusively in the
Execute Command request from Application layer when 
TRANSFER LENGTH/PARAMETER LIST LENGTH/ALLOCATION LENGTH are there in CDB to
specify the size of the data.
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Best regards
Mona
nSys
http://www.nsysinc.com
Accelerating designs
+1-510-402-4544
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-- 
----------------------------------
Best regards
Mona
nSys
http://www.nsysinc.com
Accelerating designs
+1-510-402-4544
----------------------------------