- "String Confusion" -- looks or sounds like an existing (approved or being applied for) gTLD. Must be filed by whoever owns (or is applying for) that gTLD.
- "Legal Rights" -- someone else owns a trademark this would violate. Must be filed by whoever's legal rights would be violated.
- "Limited Public Interest" -- the gTLD is immoral under recognized principles of international law. I have no idea when this could be applicable.
- "Community" -- An established community organization believes the group this gTLD is intended to target will object to it. This seems more like a vehicle for e.g. Little People of America to let ICANN know that ".midget" would be offensive.
Unfortunately there doesn't seem to be a way to tell ICANN that .lan has been widely used and will break things in a way they will listen to.