Reference area (typically planform area)

Reference length (typically Mean Aerodynamic Chord MAC). In CPACS, only one reference length exists (and is used, e.g. for all three moment coefficients. Coordinates given relative to MAC shall always use this length as MAC.

Moment reference point (in global coordinate system). The x-coordinate is typically chosen same as of the leading edge of the wing in the spanwise section having a chordlength identical to MAC. Coordinates given as %MAC shall always use this x-coordinate and length (e.g. 0%MAC = x, 100%MAC = x + length). The y coordinate is typically 0. The z coordinate is often chosen either as 0., or as z of fueselage nose or as z of middle of center fuselage part.