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Glossary for the airline industry

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

main category

A description of the category of the rule that controls the requirement. See also qualifying category.

major subcategory

One of four main subcategories of Category 10 (101-104) that states provisions for specific combination types. See circle trip, end-on-end, open jaw, and round-trip.


The city that is the origin or destination point of a journey.

market pair

The origin and destination cities of a journey.

marketing carrier

The carrier code that will appear on the flight coupon of the ticket (typically used for code share).

master source

The ATPCO database.


The data that is used to determine if the record or table is applicable.

match criteria

Portion of a query coded to find fares and use that fare amount.

maximum permitted mileage

The maximum number of miles that may be traveled for a fare component without incurring a mileage surcharge.

merchandise services

An optional service that is not associated to any passenger travel or ticket. Such a service may be priced regardless of whether the customer is holding a passenger ticket. For example, a carrier might offer logo T-shirts for sale, whether or not a ticket exists.


A key component of offer presentation, merchandising consists of product attributes used for selecting and filtering displayed offers so consumers can understand the details of the airline product.


Multilateral Interline Travel Business Agreement for airline company business travel.

Mileage currency

Currency code XXX used to file mileage awards

mileage-based fares

A fare that is not governed by a designated routing map, but instead by a maximum permitted mileage (MPM) restriction.

min/max pricing

A type of continuous pricing where airlines distribute a minimum/maximum price range, eliminating the need to pre-distribute individual prices

minor subcategory

One of four qualifying subcategories of Category 10 (106-109) that states restrictions on combination types.

mirror image

(Subcategory 102, International fares) A round-trip pricing unit consisting of two fare components, half of a round trip (Tag 2 fare) using the same tariff, carrier, rule, and fare class code on both components, and where no differing mileage and/or HIP surcharges exist on the pricing unit.


Multilateral Interline Traffic Agreements Manual 


Machine learning.

modify fares

A function that allows fares to be amended or canceled within a fares batch.