Code,Message Type,Reference
0x00,Reserved,[RFC9174]
0x01,XFER_SEGMENT,[RFC9174]
0x02,XFER_ACK,[RFC9174]
0x03,XFER_REFUSE,[RFC9174]
0x04,KEEPALIVE,[RFC9174]
0x05,SESS_TERM,[RFC9174]
0x06,MSG_REJECT,[RFC9174]
0x07,SESS_INIT,[RFC9174]
0x08-0xEF,Unassigned,
0xF0-0xFF,Reserved for Private or Experimental Use,[RFC9174]