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