Grasshopper Rhino Angle Dimension (Arc) confusion

I’m confused by the new Angle Dimension (Arc) component.

I set one arc and extractedd the parameter so I could select it. But the dimension is created on the cplane origin with a 90° arc segment?

Connecting an empty Angle Dimension to the A input results in the expected angular dimension but this seems a bit weird to me. (11.4 KB)

PS: Why is there no Serengeti category for the current version of Grasshopper, only for GH2?