| Switching must involves two different units.
| Switching while the king is under check is not allowed.
+p.
+ Notation: a switch move is marked by the capital letter 'S' followed by
+ the exchanged squares. Example in diagram: Sb8c8
+
figure.diagram-container
.diagram
| fen:1RB3k1/5ppp/8/8/8/8/8/K7: