Specifications

ATAPI For Streaming Tape QIC-157 Rev B
86
The Sense Key field is mandatory and indicates generic information describing an error or
exception condition. The sense keys are defined in Table 6-66 Sense Key Descriptions on page 89.
The content of the Information field is command-specific and is defined within the appropriate
section for the command of interest. Devices shall implement the Information field. Unless
specified otherwise, when the Valid bit is one, this field contains the difference between the number
of blocks requested by the command or commands and the actual number of blocks and filemarks
transferred to or from the medium, the residue.
The Additional Sense Length field indicates the number of additional sense bytes to follow. If the
allocation length of the Command Packet is too small to transfer all of the additional sense bytes,
the Additional Sense Length is not adjusted to reflect the truncation.
The Command-Specific Information field contains information that depends on the command that
was executed. Further meaning for this field is defined within the command description.
The Additional Sense Code (ASC) field indicates further information related to the error or
exception condition reported in the Sense Key field. Devices shall support the Additional Sense
Code field. Support of the additional sense codes not explicitly required by this specification is
optional. A list of additional sense codes is defined in Table 6-67. If the Device does not have
further information related to the error or exception condition, the Additional Sense Code is set to
NO ADDITIONAL SENSE INFORMATION.
The Additional Sense Code Qualifier (ASCQ) indicates detailed information related to the
Additional Sense Code. The ASCQ is optional. If the error or exception condition is reportable by
the Device, the value returned shall be as specified in the command descriptions. If the Device does
not have detailed information related to the error or exception condition, the ASCQ is set to zero.
Non-zero values in the Field Replaceable Unit Code field are used to define a Device-specific
mechanism or unit that has failed. A value of zero in this field shall indicate that no specific
mechanism or unit has been identified to have failed or that the data is not available. The Field
Replaceable Unit Code field is optional. The format of this information is not specified by this
Specification.
The Additional Sense Bytes field may contain command specific data, peripheral Device specific
data, or vendor-specific data that further defines the nature of the “Check Condition” status.
6.8.11.9. Sense-key Specific
The Sense-Key Specific field is defined by this Specification when the value of the Sense-Key
Specific Valid (SKSV) bit is one. The Sense-Key Specific Valid bit and Sense-Key Specific field
are optional. The definition of this field is determined by the value of the Sense Key field. This
field is reserved for sense keys not described below. An SKSV value of zero indicates that this field
is not as defined by this Specification.
If the Sense Key field is set to ILLEGAL REQUEST and the SKSV bit is set to one, the sense-key
specific field indicates which illegal parameters in the Command Packet or the data parameters are
in error.