Glossary
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## Glossary

CONS

  Connection-Oriented Network Service.

CUD

  Call User Data. Carried with a Connect Request.

DTE

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

ISO

  International Organization for Standardization.

ISO 8208

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

ISO 8878

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

LCI

  Logical Channel Identifier.

LLC-2

  Logical Link Control-Class II.

LSAP

  Link Service Access Point.

MAC

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

NLI

  Network Layer Interface.

NSAP

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

NSDU

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

NUI

  Network User Identification.

Octet

  Eight bits, a byte.

OSI

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

PVC

  Permanent Virtual Circuit.

PLP

  Packet Layer Protocol—X.25 Level III.

QOS

  Quality of Service.

RPOA

  Recognized Private Operating Agency.

SAP

  Service Access Point.

Semi-Octet

  Four bits, one hexadecimal digit.

SNPA

  Subnetwork Point of Attachment.

STREAMS

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

Subnetwork

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

TOA/NPI

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

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Appendix B. Error Codes |  | Index