{{Note|If an object touches the periodic boundary, it is assumed to extend to the neighboring unit cell. The planar mesh in In that case is extended , [[EM.Cube]] extends the planar mesh beyond the periodic boundary to ensure the current continuity. It is the user's responsibility to enforce the symmetry of the unit cell structure at the left and right boundary walls or at the top and bottom boundary wallsto accommodate the geometric continuity across the neighboring unit cells.}}