1. In a computing system, a method of operation comprising: receiving a first permutation specification of a first permutation of a first plurality of inputs; receiving a first permutation modifier; receiving an interaction specification of a first interaction between the first permutation and the first permutation modifier; and generating a second permutation specification of a second permutation of the first plurality of inputs, the second permutation resulting from the first permutation and the first permutation modifier reflective of the specified first interaction between the first permutation and the first permutation modifier.