What does the statement painted on this P-51 mean? In this video, there is a shot of the side of a P-51 Mustang.



The side of the plane is painted with:


  SERVICE THIS AIRPLANE WITH GRADE 100/150 FUEL. IF NOT AVAILABLE T.O. 06-5-1 WILL BE CONSULTED FOR EMERGENCY ACTION
  SUITABLE FOR AROMATIC FUEL


What does this mean?
They are instructions for a compatible fuel substitute for 100/150 octane fuel per Technical Order 06-5-1 if AvGas is unavailable to the service crews in an emergency.