I believe they are standard IATA airport codes (https://en.wikipedia.org/wiki/IATA_airport_code) but
I believe they are standard IATA airport codes (https://en.wikipedia.org/wiki/IATA_airport_code) but that list posted yesterday (https://speed.cloudflare.com/locations) would be a nice cf-specific endpoint to use, for as long as it's around
An IATA airport code, also known as an IATA location identifier, IATA station code, or simply a location identifier, is a three-letter geocode designating many airports and metropolitan areas around the world, defined by the International Air Transport Association (IATA). The characters prominently displayed on baggage tags attached at airport ...
