London Heathrow to KJFK Route


When I try to track any flight from EGLL to KJFK, the route only contains one “word”. This is always XTOPP, XALLE, XKANN or one or two others, always beginning with X. These do not appear to be intersections or STARs. Can anybody tell me what they mean?



Probably intersections that start or end one of the North Atlantic Routes?