I would like to "mark"/"tag" some of the surface vertices as corners for the subdivision modifier. How is this possible? If it is not possible with the GUI is there at least a Python way of accessing and setting this property?
Edit: there is two ways of manipulating the resulting surface as can be seen in the second screenshot. I would like to use the "Keep Corners" approach. How does Blender determine if it is a corner? There must be some Metadata I guess? Or is a some kind of heuristic.