The uppermost component of the windchest. Has borings in it which emerge as toe-holes. On these, the feet (for flues) or boots (for reeds) sit, and receive wind from the chest when the appropriate note is played at the console.
Wurlitzer organs used a particular sandwich construction of top-board, with cavities between the pallet and the toe-hole to allow expansion of the air, thus (partially) mimicking the effect of a classical organ’s slider sound-board.