[mc32]

My bad, my main point is that likely the most restrictive would be one of the corporate/private TLDs that are for internal use mainly. .xyz was a bad example. Maybe better is .bananarepublic

[CydeWeys]

There's literally hundreds of new gTLDs like this that only have the one required nic.tld on them and nothing else (because they haven't launched yet and might never). My team runs a couple dozen of these.

For comparison's sake, we should probably restrict ourselves to legacy gTLDs, ccTLDs, and open, launched new gTLDs.