The Sequenced DataPDU (SD-PDU) is one of sixteen Protocol Data Units (PDU) of the Service Specific Connection Oriented Protocol
(SSCOP), which is the Service Specific Convergence Sublayer
(SSCS) of the AAL layer for signaling channels. The SD-PDU is used to transmit thesequentially
numbered Physical Data Units (PDU) over the link using the Service Specific Connection Oriented Protocol.