Search for WIPO on Google. There are a lot of conflicting rulings. In general if you "register a domain in bad faith" then you are breaking the rules. If you register the domain because it is a miss-spelling then you are registering in bad faith. If you have a reason for registering the domain, other then squatting, then you are safe. But if your only reason for registering the domain is to infringe on another company then you are not in a good place.