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The outer surface, shown on Public Works Canada Greenwood Airport Zoning Plan No. S-1750, dated November 15, 1988, is an imaginary surface that consists of a common plane established at a constant elevation of 45 m above the elevation of the airport zoning reference point, except that, where that common plane is less than 9 m above the surface of the ground, the imaginary surface is located at 9 m above the surface of the ground.
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