4. cal
  6. Current rule
The Orders and Rules of Racing

PART 4 - THE RACE - (B)45 to (B)59

48. Emergency procedures

48.1 Where a yellow stop race flag indicating that it is unsafe to proceed is waved at any time in the course of a race by racecourse personnel

48.1.1 each Rider who has not passed the flag must pull up, and
48.1.2 the race shall be void.