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                                     | 
+==============================================================================+