[3,3,5]⁺. For other Coxeter groups with even-order branches, the commutator subgroup has index 2^c, where c is the number of disconnected subgraphs when all the even-order branches are removed.

For example, [4,4] has three independent nodes in the Coxeter diagram when the 4s are removed, so its commutator subgroup is index 2³, and can have different representations, all with three ⁺ operators: [4⁺,4⁺]⁺, [1⁺,4,1⁺,4,1⁺],