Bitboard checkSquares[PIECE_TYPE_NB];
};
-// In a std::deque references to elements are unaffected upon resizing
+/// A list to keep track of the position states along the setup moves (from the
+/// start position to the position just before the search starts). Needed by
+/// 'draw by repetition' detection. Use a std::deque because pointers to
+/// elements are not invalidated upon list resizing.
typedef std::unique_ptr<std::deque<StateInfo>> StateListPtr;