What is the Library?
This namespace is for fiction and roleplays related to the subject of the article. You can post them directly to the page, or you can use the page to create an index of other Library articles of different titles. For example, an article titled Battle of the Bulge maybe have a Library:Battle of the Bulge page that just details in narrative fashion the story of the battle from one or more characters' perspectives, producing a potentially flawed, unreliable narrative rather than objective truth. Alternatively, you might have different stories about the battle all told from differing perspectives and covering different parts of it, in which case you could list and link them all on Library:Battle of the Bulge
Are there any special rules?
Library articles do not have to be objective as though they were written for an in-character Wikipedia site. The other departure from the main ruleset is that you may have subpages like sandbox pages here if you want to do so for organizational purposes. For example, Library:Battle of the Bulge might be an index page which links to Library:Battle of the Bulge/The Hollowed Woods and Library:Battle of the Bulge/The River Our.
There can be multiple contributors per usual, but there is no requirement for the use of headers (though you may wish to use them anyway) or infoboxes. Ideally you will maintain adding categories and interwiki links per usual.