Ethernet II framing (also known as DIX Ethernet, named after DEC, Intel and Xerox, the major participants in its design[REF]), defines the two-octet EtherType field in an Ethernet frame, preceded by destination and source MAC addresses, that identifies an upper layer protocol encapsulating the frame data.
As this industry-developed standard went through a formal IEEE standardization process, the EtherType field was changed to a (data) length field in the new 802.3