2009

it maintains its new position relative to the parent. If the spring is
single-bodied, then the Parent Space's attachment point represents the point
in the world where the spring is attached.
Properties rollout
Parent When on, the Spring has two bodies and you can designate an object
to be the parent body. When off, the Spring is single-bodied and the point
occupied by the Parent Space sub-object is the parent.
You assign the parent object by clicking this button and then selecting a rigid
body from any viewport. Thereafter the button displays the name of the parent
body.
Child Displays the name of the second rigid body attached to the Spring. You
assign the child object by clicking this button and then selecting a rigid body
from any viewport.
Constraints | 3933