You could encode the item's location in the tree into the handle itself, though this assumes that the tree will never be rebalanced while that handle remains ac

You could encode the item's location in the tree into the handle itself, though this assumes that the tree will never be rebalanced while that handle remains active. This is basically (from what I understand) how hierarchal triangular meshes (HTM) works. The "coordinate" is a number describing the location of a coordinate's triangle within a larger triangle within a larger triangle within a larger triangle and so on until you get to an octahedron.