Mature is a simulator rating. Used in a similar fashion as the "R - X (NC-17)" ratings for movies or the "Mature" rating for video games. Certain behavior is allowed only in mature sims, such as profanity, nudity, and sexual content. Nudity and other sexual content are only allowed indoors and must not be seen by the outside world, especially from a PG sim. The TOS and CS must also still be followed.