The International Consultative Committee for Telephony and Telegraphy, the X.25 regulatory body.

Data circuit-terminating equipment.

Data terminal equipment. The user equipment (computer, terminal, and so on) connected to a network.

International Standards Organization. An international organization comprising the standards bodies of each country. ISO has issued standards on many topics, including the OSI Reference Model for networking.

A local area network, where several hosts and devices are located near one another and connected physically by cables.

Open System Interconnection Reference Model. A seven-layer model describing desirable network services and how and where they should be provided.

Packet assembler or disassember. A means of interfacing a character terminal to an X.25-based network.

Systems Network Architecture. A set of communications protocols developed by IBM for synchronous transmission of data.

A wide area network. Computers with long distances between them connected by, for example, telephone lines.

The CCITT recommendations covering network access protocols for ISO layers 1, 2, and 3 made in 1980, 1984, and 1988.