law: 3. Mode of signifying communications from the Railway Board.
  Any notice, determination,  direction, requisition, appointment, expression of opinion, approval or sanction, to be given or signified  on the part of the Railway Board. for any of the purposes of, or in relation to, any powers or functions  with which it may be invested by notification under section 2, shall be sufficient and binding if in writing  signed by the Secretary to the Railway Board, or by any other person authorized by the said Railway  Board to act in its behalf in respect of the matters to which such authorisation may relate; and the said  Railway Board shall not in any case be bound in respect of any of the matters aforesaid unless by some  writing signed in manner aforesaid.