Whats .w3n???!

Ive heard of .w3g, .w3m, .w3x but whats .w3n? I saw it listed in allowed attachment files.

It's a campaign file.

but whats it stand for? .w3m stands for war3 map, and war3 expansion

Those are my bets:

*.w3m = warcraft 3 Map
*.w3x = warcraft 3 eXpansion map
*.w3n = warcraft 3 campaigN map