With regards to rule 4: is this a blanket prohibition on kings occupying the same column, or is it based on the "flying general" move from Xiangqi? In Xiangqi if kings are occupying the same column they may capture each other. If one player's king were immobilized could the other player move such that the kings were on the same column without any pieces in between (giving check) or would this be forbidden?
With regards to rule 4: is this a blanket prohibition on kings occupying the same column, or is it based on the "flying general" move from Xiangqi? In Xiangqi if kings are occupying the same column they may capture each other. If one player's king were immobilized could the other player move such that the kings were on the same column without any pieces in between (giving check) or would this be forbidden?