In addition to the official rulesets, Games Workshop has also encouraged the writing of unofficial "house rules" by wargamers. As such, there have been a number of unofficial fan supplements and other supplementary material on the internet; the most notable of which was "The Age of the King", made by "The One Ring". Although some of its subject matter was later covered by official rulesets, it is still considered "the benchmark against which all others are measured". In many cases, supplements are written for areas where Games Workshop's licence does not extend, such as "The Silmarillion".