starting delimiter (Ethernet) (SD)
The Starting Delimiter(SD) is a delimiter character that marks the beginning of a block of a frame or a token. The SD character is used in Ethernet frames and in tokens of Token Ring and in the FDDI frame.
It is a 1 byte long data field. The Starting Delimiter immediately follows the Preamble and together with it forms the Start of Frame Sequence( SFS). The Starting Delimiter (SD) and the Ending Delimiter( ED) are each one byte long and contain the two symbols "J" and "K". For the Starting Delimiter the sequence is: JK0JK000.