Table 18
+======-========-========-========-========-========-========-========-========+
| Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|Byte | | | | | | | | |
|======+=======================================================================|
| 0 | Extended message (01h) |
|------+-----------------------------------------------------------------------|
| 1 | Extended message length (03h) |
|------+-----------------------------------------------------------------------|
| 2 | SYNCHRONOUS DATA TRANSFER REQUEST code (01h)|
|------+-----------------------------------------------------------------------|
| 3 | Transfer period factor |
|------+-----------------------------------------------------------------------|
| 4 | REQ/ACK offset |
+==============================================================================+