r network management. CMIP is an alternative to SNMP and is not widely implemented. Glossary CMIS (Common Management Information Services) CMIS (Common Management Information Services) A service interface created and standardized by the ISO for managing heterogeneous networks. CMTS (cable modem termination system) A device on which coax trunks terminate. CMTSs are linked by a common Ethernet hub, which, in turn, feeds into the IP router, which then develops the optimum path to take over an optical backbone onto the ISP. CO (central office) The physical location where local service providers terminate subscriber lines and locate the switching equipment that interconnects those lines. CO is used as a term in North America; elsewhere in the world, it is also referred to as a local exchange or Class 5 office. coax (coaxial cable) A transmission medium that consists of one (sometimes more) central wire conductor, surrounded by a dielectric insulator and encased in either a wire mesh or extruded metal sheathing. There are many varieties of coax, depending on the degree of EMI shielding afforded, voltages, and frequencies accommodated. code The conventions that specify how data may be presented in a particular system. code character A set of conventional elements established by code to enable the transmission of a written character (letter, figure, punctuation sign, arithmetical sign, and SO on) or the control of a particular function (spacing, shift, line-feed, carriage return, phase corrections, and so on). codec (coder-decoder) A device used to convert analog signals, such as speech, music, or television, to digital form for transmission over a digital medium and back again to the original analog form. One codec is required at each end of a channel. coding scheme A pattern of bits used to represent the characters in a character set, as well as carriage returns and other keyboard functions. Examples of coding schemes are ASCII, EBCDIC, and Unicode. COFDM (Coded Orthogonal Frequency Division Multiplexing) A complex tec