Air Vents on Roof Valleys

What IRC code prohibits the use of placing a Air Vent on the roofs valley. I know why your not supposed to but im having trouble seeing what code fits that regulation. Please help!

Lol, why? I’m assuming you’re talking a plumbing vent or similar?
Regardless, who cares about any codes, cutting holes in a valley for a vent is dumb.

I know that you’re not supposed to do that, but what the reason i need it is because someone did that for there house. We understand why your not supposed to but the inspector needs the code to tell the homeowners. If it was up to me i wouldn’t care, however its my company that says otherwise.