| The point on the lateral axis of an aeroplane or its extension from which the centers of gravity of all masses are referenced. |
| The point on the vertical axis of an aeroplane or its extension from which the centers of gravity of all masses are referenced. |
| The point on the longitudinal axis of an aeroplane or its extension from which the centers of gravity of all masses are referenced. |
| The distance from the reference plane to the center of gravity of an aircraft. |
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