Specifications

ATAPI For Streaming Tape QIC-157 Rev B
85
implementation of error code 71h is optional. Error code values of 00h to 6Fh are not defined by
this Specification and their use is not recommended.
Table 6-63 Request Sense Standard Data
Bit
Byte
7 6 5 4 3 2 1 0
0 Valid Error Code (70h or 71h)
1 Reserved (Segment Number)
2 Filemark EOM ILI Reserved Sense Key
3 (MSB)
4 Information
5
6 (LSB)
7 Additional Sense Length (n - 7)
8-11 Command Specific Information (Optional)
12 Additional Sense Code
13 Additional Sense Code Qualifier (Optional)
14 Field Replaceable Unit Code (Optional)
15 SKSV
(Optional)
Sense Key Specific (Optional)
16-17 Sense Key Specific (Optional)
18 Additional Sense Bytes
n
[Editor's Note: Due to hardware restrictions all sense data should be padded to a multiple of 4 bytes.]
A Valid bit of zero indicates that the Information field is not as defined in this Specification. A
Valid bit of one indicates the Information field contains valid information as defined in this
Specification. Devices shall implement the Valid bit.
The Segment Number field is Reserved.
The Filemark bit is mandatory for Streaming Tape Devices and this bit is reserved for all other
Devices. A Filemark bit of one indicates that the current command has read a filemark.
The end-of-medium (EOM) bit is mandatory for Streaming Tape Devices and printer Devices and
this bit is reserved for all other Device types. An EOM bit of one indicates that end-of-medium
condition (end-of-partition, beginning-of-partition, out-of-paper, etc.) exists. For Streaming Tape
Devices, this bit indicates that the unit is at or past the early-warning if the direction was forward
or that the command could not be completed because beginning-of-partition was encountered if
the direction was reverse.
An Incorrect Length Indicator (ILI) bit of one indicates that the requested allocation length or
selected blocks size did not match the logical block length of the data on the medium.
The Sense Key, Additional Sense Code and Additional Sense Code Qualifier provide a hierarchy
of information. The intention of the hierarchy is to provide a top-down approach for the Host to
determine information relating to the error and exception conditions. The Sense Key provides
generic categories in which error and exception conditions can be reported. The Host would
typically use the Sense Key for high-level error recovery procedures. Additional Sense Code
provides further detail describing the Sense Key. Additional Sense Code Qualifier adds further
detail to the Additional Sense Code. The Additional Sense Code and Additional Sense Code
Qualifier can be used by the Host where sophisticated error recovery procedures require detailed
information describing the error and exception conditions.