Single Comment

Looking at the ZRF, which was written by Glenn Overby himself, the code for the King looks like this:

; King
(piece
      (name King)
	(help "King: one space any direction to safe space; cannot leave fortress")
	(image Black "imagesABChessBK.bmp" White "imagesABChessWK.bmp")
      (moves
	((free) n (available) (verify (in-zone? fortress)) add)
      ((free) e (available) (verify (in-zone? fortress)) add)
      ((free) s (available) (verify (in-zone? fortress)) add)
     	((free) w (available) (verify (in-zone? fortress)) add)
      ((free) ne (available) (verify (in-zone? fortress)) add)
      ((free) nw (available) (verify (in-zone? fortress)) add)
      ((free) se (available) (verify (in-zone? fortress)) add)
      ((free) sw (available) (verify (in-zone? fortress)) add)
	(n (while empty? n) (verify (piece? King)) add)
      )
)

The free command is used to verify that a piece is not immobilized by an Immobilizer. This command is used before every type of movement except the last one. This last one is for capturing the enemy King by moving forward as a Rook. Therefore, an otherwise immobilized King can still threaten check against the enemy King, and this prevents the enemy King from checking it by moving to the same file with nothing in between them. Therefore, the rule against Kings being in the same file with nothing in between them is absolute, and there is no exception for checking an immobilized King with the other King.