This section specifies the Logical Link Control (LLC) Sublayer protocol data unit (PDU) structure for the CEBus Network. The LLC PDU (LPDU) is the unit of data exchanged between peer LLC entities. The LPDU consists of an "LPDU Header" and an "LLC Service Data Unit"
(LSDU). The LSDU may be a Network Layer Protocol Data Unit (NPDU) to be exchanged
between peer Network Layer entities. The LPDU Header is a unit of data which the LLC
Sublayer appends to the LSDU to properly deliver the LSDU to its destination. Upon reception
of an LPDU, the LPDU Header is stripped away by the receiving LLC Sublayer, and the LSDU is
passed to the destination's Network Layer. (Note that the LPDU Header is currently null.)