other building and a purchaser other than the Board shall be in the prescribed form.[41/98](3) Any contract, agreement or other document which is made on or after 20th November 1998 in contravention of subsection (1) or (2) shall be null and void.[41/98]Flat, house or other building not to be sold, mortgaged, etc., without consent of Board50.???(1) No flat, house or other building which has been s