Thank you for your comment. The tagging format I’m using is intentional.

Circumference is the total distance around a tree trunk, measured by wrapping a tape around it.

Diameter is the straight‑line distance that passes through the center of the trunk from one side to the other.

I only have data for a range of diameters, so I don’t have exact measurements or the corresponding circumferences.

Soon I’ll formally propose the tags diameter:crown= and diameter:trunk=. I’m already applying this tagging scheme in a limited area.