Tournament rules

[Avivs]

does anyone knows what are the rules regarding the number of raises allowed in a round of betting at a No Limit Texas Hold'em tournaments?
It seams like every place I play have different views.
Some places do not limit the number which means anyone can either fold, call or raise when it's their turn.
Another place I play at limit it to a max of a bet and 3 raises per round like in Limit games which means that if you are in late position with AA and the pot have been raised 3 times before it's your turn to act you can't reraise to drive out opponents...
Are there fixed rules or can any poker room make their own?

[crockpot]

there should be no restriction on the number of bets and raises per round in a good big-bet setup.

i've never played a no-limit game in person, but i've yet to see a website that places a restriction on this, and it would annoy me if i found one.