SPC sense data problem

David Hawks Hawks at iomega.com
Wed Apr 28 10:43:51 PDT 2004

* From the T10 Reflector (t10 at t10.org), posted by:
* "David Hawks" <Hawks at iomega.com>

We have run into a confusing area of the SPC-3 specification regarding
sense data.  I am referring specifically to the descriptions of the

Section 4.5.3 describes the "Fixed sense data format".  Here we are
directed to section for the description of the four-byte

Section is the definition of the "Information sense data
descriptor".  This descriptor contains an eight byte INFORMATION field.
The INFORMATION field is described as below (from SPC-3 Revision 18):

The contents of the INFORMATION field are device-type or command
specific and are defined in a command
standard (see 3.1.17). When a four byte quantity is stored in the
INFORMATION field, the first four bytes shall be zero.

Because the INFORMATION field in the "Information sense data descriptor"
is eight bytes, this makes sense.  However, when referring to this
section for the four byte INFORMATION field of the "Fixed sense data
format", setting the first four bytes to zero does not work.  The same
problem exists for the COMMAND-SPECIFIC INFORMATION field in section

David Hawks
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