to Caissus:
No wonder about that, it is correct PGN. The problem is the moment, when castlings could or should happen! P.S.: I have written something on FRC-FEN to cover situations, where the Rook with castling rights is not the outermost one. BrainKing is merely encoding starting positions, so it is not relevant here. But if you want to encode even exotic positions with FEN, you will need a tool like Smirf or the FullChess FEN Editor.