Siano has suggested that the directed dimensions of Huntley be replaced by using orientational symbols 1 x 1 y 1 z to denote vector directions, and an orientationless symbol 1 0. Thus, Huntley's L x becomes L1 x with L specifying the dimension of length, and 1 x specifying the orientation. Siano further shows that the orientational symbols have an algebra of their own. Along with the requirement that 1 i = 1 i, the following multiplication table for the orientation symbols results: