Well-Known Text
Drag a white vertex to move it, drag a faint midpoint to add one, right-click a vertex to remove it. The toolbar top right draws new shapes, moves a whole shape, or cuts a hole. The text rewrites itself on every change.
Examples
Check
StatusNothing drawn
Precision
6 decimal places is about 10 cm on the ground. Anything beyond that lengthens the string without describing a real boundary, and long strings are the ones that get truncated somewhere between a form and a database.