In the attachment to bug 62, Stan wrote:
The concepts for constraint can be difficult to grasp. There are various ways to think of constraints, so this section really needs to be reviewed carefully. To help the reader, some specific examples would help.
Since the attachment frames can be hard to grasp, we could add a paragraph to say how to implement a drive model using existing constructs:
Create fixed joint. specify a maximum torque or finite spring force in extra.
then animate the attachment's transform (translate and rotate).
This concrete example would help people understand how the joint frames work.
Need text written out for this example and some actual xml to go with it.