I don't think this comes up often in practice, but unless I'm mistaken one's king may not be on a square that is attacked by any of the opponent's pieces. AFAIK, this even includes the situation when the said opponent's piece is immobilized due to its being pinned against its own king. Thus a checkmate could occur even when the checkmate hinges on a king's being forbidden to escape to a square "attacked" by an opponent's piece that is at the time immobilized by a king pin. Is this correct? It won't change the course of chess very much, but if this is possible I think the rule should be changed so that the king is allowed to move to any unoccupied square unless the opponent could conceivably "take" the king on that square on the very next move. Comments? --Dan