This document describes a communication interface between a channel and I/O control units that utilize the Single-Byte Command Code Sets (SBCCS) as implemented in a wide range of data processing systems. It employs information formats and signaling protocols that provide a uniform means for communicating with various types of I/O control units, facilitating a high bandwidth, high performance, and long distance information exchange environment. The signaling protocols and information exchanges are defined at a layer (FC-4) to compatibly utilize the link services and other functions provided by the ANSI Fibre Channel Physical and Signaling Interface (FC-PH) architecture (ANSI INCITS 230-1994, reference [1]). This FC-4 Upper Level Protocol is referred to as the Fibre Channel-Single- Byte-3 Command Code Sets Mapping Protocol (or for brevity, SB-3). FC-SB-3 is an update to FC-SB- 2. (See reference [6].)