ld be required. These would essentially be wasted bits. CCITT makes use of these bits to provide framing overhead, status information, and control information. A frame (step 1 conversion) consists of 10 octets (10 X 8 = 80 bits). Six octets carry user data, the first octet is all Os for frame alignment, and bit 1 of the remaining 9 octets is set to 1. There are 15 overhead bits. Nine different frames accommodate the various data rates, and each frame has 80 bits (10 octets). The recommendation also covers conversion of start-stop data rates including 50, 75, 110, 150, and 300 bps and the standard rates up through 19.2 kbps (Ref. 18). 10.10 WHAT ARE DATA PROTOCOLS? To get the most out of a network, certain operational rules, procedures, and interfaces have to be established. A data network is a big investment, and our desire is to get the best return on that investment. One way to optimize return on a data network is by the selection of operational protocols. We must argue that there are multiple tradeoffs involved, all interacting one with another. Among these are data needs to be satisfied, network topology and architecture, selection of transmission media, switching and network management hardware and software, and operational protocols. In this section we will focus on the protocols. In the IEEE Standard Dictionary (Ref. 1), one definition of a protocol is the following: "a set of rules that govern functional units to achieve communication." We would add interfaces to the definition to make it more all-encompassing. In this section we will trace some of the evolution of protocols up through the International Standards Organization 13 Clear DSO channel is a DSO channel with the signaling bits disabled. 10.10 WHAT ARE DATA PROTOCOLS? (ISO), OSI and its seven layers. Emphasis will be placed on the first three layers because they are more directly involved in communication. Protocols should not be confused with formats. Formats typically show a standard organization of bits and octets and describe the function of 