market– a specific airport pair, such as LHR-ATH. (You will sometimes hear an airport pair called a “sector”.) 

point of sale – aka “POS” – normally the country in which a ticket was purchased, generally expressed as a 2-digit ISO country code, such as DE for Germany. POS is usually the country in which the selling travel agent is located. Sometimes the point of sale is more granularly considered as the exact city of sale (e.g., LON for London), and sometimes the term point of sale is used interchangeably with Point of Origin, though that is a conflation as POO has a different technical meaning. 

point of origin – aka “POO” or “POORG” – the airport from which a passenger originated, on their first trip. For example, if a passenger flies JFK-LHR, then a week later, LHR-JFK, the point of origin, for both trips, is JFK. Normally, the POO is considered to be the origin airport of the first coupon on a ticket. 

region pair – a general regional travel category such as Europe-to-Asia. Sometimes region pairs are indicated by first-digit of WAC codes, such as 4-7 indicates Europe to Asia. Sometimes region pairs are expressed nondirectionally, such that 4-7 indicates both Europe to Asia and Asia to Europe. The lower number is first in the pair. 

station – a specific airport, sometimes in the context of a “node” on an air network.  

airport code– a three-digit code indicating the airport, such as IAD = Washington Dulles, ORD = Chicago O’Hare, LHR = London Heathrow, etc., etc. We use airport code for origin, destination, connect points, and through points in our output file.

city code / metro code – A 3-digit “airport” code that reflects a city and may cover multiple airports, e.g., NYC = New York (includes JFK, LGA, EWR); CHI = Chicago (includes ORD, MDW); WAS = Washington DC (includes DCA, IAD, BWI); LON = London (includes LHR, LGW, STN, LTN) 

WAC code – a 3-digit “World Area Code” as defined by the US Department of Transportation. For example, 450 = Italy. WAC codes are grouped by region, as indicated by the first digit, as follows – 0=USA, 1=Central America & Mexico, 2=Caribbean, 3=South America, 4=Europe, 5=Africa, 6=Middle East, 7=Asia, 8=Oceania, and 9=Canada & Greenland.