Reference points are locations on a vehicle which correspond to specific measuring points. Use the reference points when checking the vehicle structure.

Dimension charts may use the leading edge of a hole, center of a bolt head or nut, etc. as a reference point. A description and location chart will tell you how and where the measurements should be taken. The most accurate reference point is a gauge hole or a control hole used by the assembly plant in order to control tolerances when the vehicle was built. Refer to Frame Control Hole Description for more information about control holes.