This document provides engineering, operational, and maintenance guidance to users and suppliers of
Optical Fiber Digital Transmission Systems for telecommunications applications. The function of the
fiber systems considered in this document is to relay digital signals between defined digital interfaces via
an optical fiber link. The information presented applies to optical fiber systems using multimode graded
or step index fibers. Single-mode systems are under consideration and will be incorporated in a future
issue of this document. Bidirectional systems, in which both directions of transmission use a common
optical fiber, will also be considered in a future issue of this document.