This document contains the details of the ANSI/CEA-709.4 standard. In conjunction with ANSI/EIA-709.1-A Control Network Protocol Specification, EIA-709.4 defines a complete 7-layer protocol stack for communications on an EIA-709.4 single-fiber (half-duplex) fiber-optic channel. EIA-709.4 specifies the physical layer (OSI Layer 1) requirements for the EIA -709.4 fiber-optic channel which encompasses the interface to the Media Access Control (MAC) layer and the interface to the medium. The single-fiber channel implemented as specified in EIA-709.4 allows two nodes to communicate bidirectionally across a single piece of fiber cable.
More Information on this standard can be found here.