#altitude.elevation__height  elevation especially above sea level or above the earth's surface
  supertype:  #elevation  distance of something above a reference point
  subtype:  #level  height above ground: "the water reached ankle level"; "the pictures were at the same level"
  subtype:  #lowest_layer_of_clouds__ceiling  (meteorology) altitude of the lowest layer of clouds
  subtype:  #plane_maximum_altitude__planemaximumaltitude__ceiling  maximum altitude at which a plane can fly (under specified conditions)
     subtype:  #absolute_ceiling  the maximum altitude at which an air plane can maintain horizontal flight
     subtype:  #combat_ceiling__service_ceiling__serviceceiling  altitude above which a plane cannot climb faster than a given rate

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