I have looked at it, but it is not what I wanted, the figure has no joints. What I want is move the center of the joint.

For moving the pivot point I can use some of the the "offsetN" k values. The interesting thing is that I can have more duplicated channels and this is very useful, for example I can have two rotation dials, one that rotates the object around itself and the other dial that rotates around the center of the scene (of course the object is not in the center).

To explain what I want, for example I have a tube with enough segments to have a good mesh definition, not body parts, each body part can have a lot of segments.

I can set the joint center in any place of a body part, not necessarly at the junction with the other body part, the center can be outside the mesh. This center will define the point of bending of the mesh.

If the tube is along the Y axis, normally the joint X,Z center is set at the center of the tube. When I bend the tube to the right as the bending angle increases the result become not good, I can use buldges to improve the bended shape.

Now, if I can move the joint center to the right, the bended mesh becomes much better and I can achieve greater angles (90 degrees or more) and the mesh still continue to look good. If I want to bend the tube to the left I move the joint center to the left. In either case the translation is proportional or some function of the bending angle.

Stupidity also evolves!