What is the P&ID symbol of a double block and bleed valve (DBB) (Not two independent valves and a bleed valve) ?

[wbic1]

Is there a P&ID symbol for a double block and bleed (DBB) valve being used on a P&ID? I am not asking for symbols which show two seperate valves and a bleed valve. The symbol I am looking for is one symbol which represents a DBB valve.