CIP swap parity: (−1)^N = 1 at N=2 (even preserves R/S); (−1)^N = −1 at N=3 (odd inverts)

(−1)^N takes value +1 for N = 2 (even swaps preserve R/S) and −1 for N = 3 (odd swaps invert R↔S). Canonical pins: parity symbol (−1)^N; parity at N=2 (integer 1); parity at N=3 (integer −1).