[ODE] Question to the ODE V0.5 User Guide.

[TK]

Hello , People.

I have a question in the ODE V0.5 User Guide.

At 7.3.1 Ball and Socket
>void dJointGetBallAnchor (dJointID, dVector3 result);
>Get the joint anchor point, in world coordinates. 
I understood here.

>This returns the point on body 1. If the joint is
>perfectly satisfied, this will be the same as the >point
on body 2.
I can't understand above.
What relation between bodies' point and axis coordinate?