The points in the plane can be represented by homogeneous coordinates. A point has homogeneous coordinates ["x" : "y" : "z"], where the coordinates ["x" : "y" : "z"] and ["tx" : "ty" : "tz"] are considered to represent the same point, for all nonzero values of "t". The points with coordinates ["x" : "y" : 1] are the usual real plane, called the finite part of the projective plane, and points with coordinates ["x" : "y" : 0], called points at infinity or ideal points, constitute a line called the line at infinity. (The homogeneous coordinates [0 : 0 : 0] do not represent any point.)