sorting - the sorting type to use when rendering the views in this paper (i.e. In what order should the views be rendered?).

The SVG 1.1 format does not have built-in z-index functionality, so JointJS implements it programmatically. You can set the z-index directly using using regular Backbone set('z')/get('z') methods or through element.toFront()/element.toBack()/link.toFront()/link.toBack() methods. See the element Z documentation for more information.

The Paper object exposes a sorting object with three values that may be used as values of this option: