The acronym VNF stands for Vertices 'N' Faces. You have probably already come across the concept of vertices and faces when working with the OpenSCAD built-in module polyhedron(). A polyhedron() in it ...
The master branch only contains the *Model.xml files, not the compiled NodeSet2.xml files. On every push to a branch, an is executed and the resulting model files are pushed back to the branch 'master ...