The north direction as defined by Magnetic North Pole at the time of the measurement. The Magnetic North Pole is the direction that a magnet points to when freely rotating.
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grid north
The north direction is defined by the coordinate grid in the projection coordinate system.
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true north
The north direction as defined by the true North Pole. The true North Pole is an average of the actual measured north axis, which is the axis of rotation of the earth.