 Similarly in the class B case (with "n"(3) = 0), Bianchi type VIh ("a"="h", "n"(1)=1, "n"(2)=–1) projects to the fourth quadrant of the horizontal plane and type VIIh ("a"="h", "n"(1)=1, "n"(2)=1) projects to the first quadrant of the horizontal plane; these last two types are a single isomorphism class corresponding to a constant value surface of the function "h" = "a"2("n"(1)"n"(2))−1.A typical such surface is illustrated in one octant, the angle "θ" given by tan"θ" = |"h"/2|1/2; those in the remaining octants are obtained by rotation through multiples of "π"/2, "h" alternating in sign for a given magnitude |"h"|.Type III is a subtype of VIh with "a"=1.