Hi Frederick, dimensions are projected onto the current construction plane. You can set the construction plane by using View > CPlane, if you set it so the cplane's origin point is on that surface plane then they will go on there when you draw a new one.

When you're done you can right-click on View > CPlane to reset back to the default world origin/world axis construction plane.

When you place the construction plane for this type of purpose, you probably will want to disable the "Align to objects" checkbox option:


- Michael