5 Quantities library [qties]

5.8 Types [qty.types]

5.8.3 Class template quantity_point [qty.point.type]

namespace mp_units { export template<unspecified> class quantity_point { unspecified }; }
A quantity point type is a specialization of quantity_point.
Let Q be a quantity point type.
Q​::​point_origin represents the origin point of a position vector (IEC 60050, 102-03-15).