A bet is void if –

(a) at the time the bet is made, it is impossible for the bettor to win the bet; or

(b) it is made after the relevant race has been run or, in the case of a multiple bet, the first relevant race has been run; or

(c) the relevant race is a walk-over or, in the case of a multiple bet, the first relevant race is a walk-over; or

(d) it is declared void by the controlling stewards (whether as a result of an inquiry or otherwise); or

(e) it is void under another provision of the Act or these regulations.