Connection-Oriented Network Service.

Call User Data. Carried with a Connect Request.

Data Terminal Equipment. Used in this guide for the X.121 address of the line connecting the equipment to a packet-switched network.

International Organization for Standardization.

Standard for X.25 Packet Level Protocol for Data Terminal Equipment.

Standard that defines the use of X.25 to provide the OSI connection-mode network service.

Logical Channel Identifier.

Logical Link Control-Class II.

Link Service Access Point.

Medium Access Control. Used in this guide to refer to the physical Ethernet address.

Network Layer Interface.

Network Service Access Point. An ISO address, a string of 40 hexadecimal digits or semi-octets.

Network Service Data Unit—the unit of data passed across the interface to the network layer.

Network User Identification.

Eight bits, a byte.

Open Systems Interconnection. The ISO definition of a communications system providing reliable, data transparent, host-independent communications service.

Permanent Virtual Circuit.

Packet Layer Protocol—X.25 Level III.

Quality of Service.

Recognized Private Operating Agency.

Service Access Point.

Four bits, one hexadecimal digit.

Subnetwork Point of Attachment.

STREAMS is a set of system calls, kernel resources, and utility routines that create, use and dismantle a stream.

In this guide, this term refers to the network accessed via a single physical link or a single Ethernet interface.

Type Of Address/Numbering Plan Identification. An address format that provides increased addressing capacity suitable for communication with ISDNs.