- castle: if both the king and the right-most (from white player perspective) rook
- haven't moved yet, and if nothing stand in the path from king to rook, and if the
- squares f1 and g1 are either free or occupied by the king or rook implied, then
- the king can go to g1 while the rook moves to f1. Note that since positions are
- shuffled one of these two pieces may apparently not move.
- The same can be done on the other side (left-most rook), and end squares are c1
- for king and d1 for rook. The former is small castle, and the latter large castle.
+ castle: if both the king and the right-most (from white player perspective)
+ rook haven't moved yet, and if nothing stand in the path from king to rook,
+ and if the squares f1 and g1 are either free or occupied by the king or
+ rook implied, then the king can go to g1 while the rook moves to f1. Note
+ that since positions are shuffled one of these two pieces may apparently
+ not move. The same can be done on the other side (left-most rook), and end
+ squares are c1 for king and d1 for rook. The former is small castle, and
+ the latter large castle.