X3 does not have a permutation operator (^)

It performs a specific function (any of, in any order, each one a single time).

It existed in Qi, but is absent from X3.
I don't think there's an easy way to implement it generically building on the other possibilities of X3.

Start by comparing the existing Qi permutation operator with the available X3 parser-combinator operators. Determine the intended semantics for matching each alternative once in any order and whether it can be implemented generically in X3. Done means a documented operator design and coverage for its permutation behavior.

Written by the indexing model from the issue text.