How to make a DimAngle on a custom 3D plane?

How can I make a dimension for angle that is measured on the shown custom plane, and NOT on the X-Y plane? DimAngle has no such feature.

Hi -

That’s correct. All dimensions use the current construction plane. You can run the CPlane command and use the Object option to create a temporary CPlane on that object. You can then place the dimension.
-wim