3.1.5.5 DataBody Payload
The DataBody payload is defined in section 2.2.1.2.7 and is the second part of the DATA payload associated with the DATA flag.The DataBody payload contains the actual data and is the last optional payload in a Packet Layout.
Refer to section 3.1.1.1.3 for the procedure for converting ChannelSeqNum back to its full ranged value.
The channel sequence number is an incremental number injected by the reliability controller for the purpose of packet loss recovery (section 3.1.1.2.4). When a packet is declared lost, the same packet is retransmitted with a new sequence number. But since the channel sequence number is part of the data payload, it remains the same through the retransmission, which allows the Receiver reliability controller to match the retransmitted packet with the lost packet. This is different from the SeqNum in DataHeader which is different every time a retransmission packet is sent.