Big gap under doors?

[Gon2Ski]

Is the two inch gap below the bunk room door and the pocket door above the stairway where you enter the bath/bedroom a mfg/builders safety code thing allowing fresh air to pass incase of carbon monoxide/propane gas? Just curious! :?

[Crazymo]

I think its just a standard? but I could be wrong

[campbud]

I had a dealer tell me once that they were made like that so when the furnance is on the air can flow better. I dont know how true it is though but I can find no reason as to why they would make the doors like that!