3.1.5.4 DataHeader Payload
The DataHeader payload is defined in section 2.2.1.2.5, and is the header part of the DATA payload associated with the DATA flag. The DataHeader payload is sent by the Sender when there is upper layer data to be sent.
Refer to section 3.1.1.1.3 for the procedure for converting DataSN back to its full ranged value.
Upon receiving a packet with this payload, the Receiver is expected to acknowledge this sequence number back to the Sender through an acknowledgment packet, either immediately or in a delayed fashion, by accumulating a number of subsequent packets to arrive for an array of acknowledgment information and packaging them together into a single acknowledgment payload.