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The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface.
Added 9/9/2014 4:47:48 AM
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Magnetic declination or variation is the angle on the horizontal plane between magnetic north and true north.
Added 9/9/2014 4:48:20 AM
This answer has been confirmed as correct and helpful.