Table 21
+======-========-========-========-========-========-========-========-========+
| Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|Byte | | | | | | | | |
|======+=======================================================================|
| 0 | Operation code |
|------+-----------------------------------------------------------------------|
| 1 | Logical unit number | (MSB) |
|------+------------------------------ ---|
| 2 | Logical block address (if required) |
|------+--- ---|
| 3 | (LSB) |
|------+-----------------------------------------------------------------------|
| | Transfer length (if required) |
| 4 | Parameter list length (if required) |
| | Allocation length (if required) |
|------+-----------------------------------------------------------------------|
| 5 | Control |
+==============================================================================+