Structures such as threads (which are just circles rotated a round a vertical axis) are generated with much more fidelity in this format than if they required triangulation.
As the structures are already sliced, this would also allow path planning algorithms to more quickly generate gcode.
I should think that your motion planning engine already works in the slice domain, so this should not be an expensive feature to add.
Here is a reference to the 3MF slice specification:
https://3mf.io/wp-content/uploads/2016/ ... ceSpec.pdf
