In the case of affine Coxeter groups like , or , one mirror, usually the last, is translated off the origin. A translation generator τ 0,1 (and matrix T 0,1) is constructed as the product of two (or an even number of) reflections, including the affine reflection. A transreflection (reflection plus a translation) can be the product of an odd number of reflections φ 0,1,2 (and matrix V 0,1,2), like the index 4 subgroup : [4,4 ] = .