Two-dimensional versions of this problem have also been studied. A 2D orthogonal point-drawing of a graph maps each vertex to a unique point of the 2D square lattice, and maps each edge to a lattice path between the endpoints; the paths are allowed to intersect at common endpoints and at proper crossings (points at which two paths meet but do not bend), but must be edge-disjoint. Every graph with maximum vertex degree Δ≤4 has a 2D orthogonal point-drawing with at most two bends per edge, and furthermore within a 2n×2n rectangle of the grid [Sch95]. On the other hand, as in 3D, any drawing of K5 uses at least two bends on at least one edge [Sch95], so two bends is again best possible. For planar graphs, we can ask for 2D orthogonal point-drawings that have no (proper) crossings. In this case, again there are drawings with at most two bends per edge, unless the graph has a connected component isomorphic to the icosohedron, in which case three bends per edge is the best possible [BK98,LMS98].