Well, technically there are layers and layers of rights - like the layers of an onion (peel back too many layers and it all ends in tears).

The first layer starts when a mark is "first used in commerce", and it goes on from there. A registered mark is a whole other layer entirely. Others have said that Linden Lab has asserted trademark rights that do not exist, or that aren't yet available to them.

It seems unreasonably complicated for the layperson to go about their business and know what they can say or do or write.