I have to say, I'm very confused. There is possibly something very cool here, but confusion reigns supreme for me right now.

In the "A", or "signed angle outside" example [1], what defines the position of the points making the A?

Also, the amount of text required to make that examples seems huge, when you consider the >600 lines of style. How is this advantageous over SVG, which can also be semantically-meaningful?

1. https://penrose.cs.cmu.edu/try/?examples=walk-on-spheres%2FS...