Elliptical dimension lines for isometric views of circles?

I'm drawing a section of a disc, viewed from an isometric perspective.  So the entire disk would look like an ellipse.  But in my diagram, I'm only showing a section of that disc.  I.e., if the section is 50 degree wide, then in my diagram 310 degrees of the original ellipse have been removed.

I'd like to provide a dimension arc that to indicate how many degrees make up the section.  I'd like that dimension line to appear as though it's in the same plane as the disc it's documenting.  Anyone know how to do this in LibreCAD?

I imagine I can fudge it by drawing the dimension primitives on my own, but I don't want to fight against LibreCAD's intended way of solving this problem.

Also FYI, I'll be supplying my own text for the dimension's label, so I don't need LibreCAD to do any kind of accurate angle calculations for me in this case.

arc-section-isometric.dxf

Here's a dxf file showing what I want to dimension.

Very interesting idea.

we know the isometric grid support is not complete without dimension also in isometric.

Since LibreCAD is currently 2D only, we need to decide how to support this kind of features.

Thanks for reporting!