Fictional universes are sometimes shared by multiple prose authors, with each author's works in that universe being granted approximately equal canonical status. For example, Larry Niven's fictional universe Known Space has an approximately 135-year period in which Niven allows other authors to write stories about the Man-Kzin Wars. Other fictional universes, like the "Ring of Fire" series, actively court canonical stimulus from fans, but gate and control the changes through a formalized process and the final say of the editor and universe creator.