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Glossary for the airline industry

From A-Z, this glossary covers definitions and explanations for common airline industry terminology.

T/C Lock

Tariff/Carrier Lock. A feature for US/CA fares that may be set for a batch with action type Apply or Release.


A group of data elements. See supporting table for a list of table numbers and names.


In the Fares system, defines whether a fare can be used as a one-way fare or a round-trip fare.

Tag 1

1. (domestic US/CA fares) A one-way fare. 2. (international fares) A one-way fare that may be doubled and halved (can be used in one-way, round-trip, circle-trip, and open-jaw pricing units).

Tag 2

1. (domestic US/CA fares) A published round-trip fare. 2. (international fares) A published round-trip fare (may only be used in round-trip, circle-trip, or open-jaw pricing units).

Tag 3

(international fares) A one-way fare that may not be doubled and halved (may only be used on one-way pricing units).


1. A database that contains data defined by system, geographic scope, and distribution process.

2. Information filed with governments when a legal filing is required.

tariff number

Geographic areas of the world are assigned tariff numbers and names. Fares for markets within that geographic area are distributed with the assigned tariff number.

tariff owner

The organization identified as the owner of the tariff.

tariff-owner tariff

A tariff where the tariff owner is an organization that may be different from the carrier whose data is in the tariff.

tax component

The end points of the travel associated with a tax as determined by Tax Rules (Record X1) processing.

Tax Summary

Formerly the Ticket Tax Box Service (TTBS), Tax Summary is an online display of current and historical taxes, fees, and charges for up to two calendar years.


Traffic Conference.


1. Transaction control number. 2. ATPCO's Ticket Exchange Service.



technical standards

An established norm or requirement for a repeatable technical task. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes, and practices. The standardization process may be by edict or may involve the formal consensus of technical experts.

terminal points

Fare break point; the ends of a fare component. Typically used when a fare has not yet been assessed for the fare component.

third freedom

The right for an air carrier to put down in the territory of another state passengers, freight, and mail taken up in the state in which it is registered.

through fare

A fare applicable for travel between two consecutive fare breakpoints via an intermediate point. A through fare can be a published/specified fare or a constructed/unpublished fare.

ticket-related services

An optional service that must be associated to a specific passenger ticket, though not necessarily a specific flight. For example, a service for lounge access might be provided only if the passenger holds a ticket confirming travel into or out of the airport where the lounge facility exists.