The Hinge may be oriented using a direction vector from the Hinge location. Note that the entries in the Abs or Rel values do not have to be unit normal vectors and will be automatically normalized in the inactive fields. There is a difference between the Reference under the Vectors heading in the Orient tab and the selected Reference Vector at the bottom of the Orient tab. The Reference direction under the Vectors header determines which Hinge axis is used to define the zero angle deflection. The Reference Vector at the bottom of the Orient tab is the global X, Y, or Z direction where the Reference is oriented. For example, if X is the rotation axis and Y is the Reference (zero) direction, choosing Z as the Reference Vector will align the green Y axis with the global Z direction.