Table 228

+=========-==================+
|   Code  |  Pacing protocol |
|---------+------------------|
|    0h   |  None            |
|    1h   |  XON/XOFF        |
|    2h   |  ETX/ACK         |
|    3h   |  DTR             |
| 4h - 7h |  Reserved        |
| 8h - Fh |  Vendor-specific |
+============================+