...no such place 😉
You have to analyze the ones in the accesories library...
Regarding the polygonal element accesories - the addon fills the 2 matrix parameters with the coords of the vertices...
The curved edges are faceted...(I was trying to reverse the process, but had no time - maybe someone did?)
Anyway - just ask - I did some findings regarding at least of the polygonal ones.
Piotr