The correct method is to file a flight plan with an Oceanic Entry Point (OEP), then the name of the NAT Track, e.g.
"NAT A" for NAT Track Alpha, and the Oceanic Exit Point (OXP).
A typical routing would be: DCT KONAN UL607 EVRIN DCT MALOT/M081F350 DCT 53N020W 52N030W NATA JOOPY/N0462F360 N276C TUSKY DCT PLYMM.
Using a NAT Track, even when they are active in the direction an aircraft is flying, is not mandatory.North Atlantic Tracks are published by Shanwick Centre (EGGX) and Gander Centre (CZQX), in consultation with other adjacent air traffic control agencies and airlines.The day prior to the tracks being published, airlines that fly the North Atlantic regularly send a preferred route message (PRM) to Gander and Shanwick.Westbound tracks (valid from UTC to UTC at 30W) are indicated by the letters A, B, C, D etc.(as far as M if necessary, omitting I), where A is the northernmost track, and eastbound tracks (valid from UTC to UTC at 30W) are indicated by the letters Z, Y, X, W etc.