The depth of the Transform in the hierarchy where zero is the root. When the _transformTweenMode is anything other than PhysicsWorld.TransformTweenMode.Parallel, all PhysicsBody.TransformWriteTween are sorted into ascending depth order so that writing the transforms in tween order will result in the deeper children correctly overwriting any parent transform writes. This is NOT set when the _transformTweenMode is set to PhysicsWorld.TransformTweenMode.Parallel and will be zero.

public int transformDepth { readonly get; set; }