Public Domain

After the Two and a Half Month Gap, all of the characters whose Writers weren't around anymore were declared "Public Domain", free to use by any LNH writer. This turned out to be problematic, both because it conflicted with the actual, legal meaning of "public domain", and because, occasionally, writers did come back – and weren't necessarily pleased with how their characters were being used.

Eventually, the Public Domain level was retired, replaced with the Reserved/Not Reserved system; even later, the Free For Use category was created, for characters that can safely be used as a common resource, either through their writers explicitly putting them there or through decades of tradition.

LNHY has a "Public Domain" level of usability, but characters have to be explicitly put into that level by their writers. For the full details, see Character Usability.