hingePoint definition for trailingEdgeDevice in CPACS 2.3.1 and CPACS 3.0

[GodertdeZoetenGKNFokker]

For a TED, the innerHingePoint and outerHingePoint locations are defined by a hingeXsi and hingeRelHeight coordinate in CPACs 2.3.1 and CPACS 3.0. I want to check whether I interpret this coodinate the correct way.

In the documentation it says that the xsiHinge is relative to the parent chord.
Right now, I take this chord to be measured in the direction of the innerBorder or outerBorder line. Is this correct or should it be taken in the wing x direction ? (the borders and wing x axis are not necessarily aligned). In the latter case, at which point (y-coordinate) on the innerBorder or outerBorder line should the wing chord be taken?

For the hingeRelHeight, I was wondering which plane should be used to measure the thickness of the airfoil? Should this be a plane perpendicular to the chord of the wing?

Lastly, I have a question regarding the hinge axis coordinate system. In the documentation, the following is stated:
"This is defined as follows: The x-hinge coordinate equals the wing x-axis. The y-hinge coordinate equals the hinge line axis (see above; positive from inner to outer hinge point). The z-hinge line is perpendicular on the x-hinge and y-hinge coordinate according to the right hand rule. The rotation of the control surface is defined as rotation around the positive y-hinge line.

When I was trying to implement this, I realized that if the y-axis of the hinge axis system is aligned with the hinge line, the wing x-axis is not necessarily perpendicular to the y-axis of the hinge axis system. For instance, if the outerhingePoint has a different x coordinate than the innerHingePoint, the wing x-axis will not be perpendicular to the hingeLine.

Hence, I have now done the following:
The hinge y-axis is aligned with the hingeLine.
The hinge z-axis is aligned with a vector that is perpendicular to the hinge-line and which y and x components have the same ratio as the hinge line direction.
The x-axis completes the axis system following the right-hand rule.

I was wondering what your thoughts were on this approach?
If anything is unclear I am more than happy to clarify.