Venting rules

Hi All,

Are there any specific rules dictating maximum fittings used on a vent line to get around obsticles when there are no other options/paths to take?

Are there any specific angles and configurations that should be avoided etc

obviously the best route would be as clean and direct as possible!

many thanks
novicepiper

Vent must slope continuosly down from the roof to the drain connection. No bellies. Any horizontal runs must be 6" above the flood rim of the fixtures served, and must slope slightly back to the drain.