The OGL System is an open roleplaying game system, published by Mongoose Publishing. It is in fact the d20 System, but it was rewritten in order not to contain any licensed material; for example, the term "d20 System" was systematically replaced by "OGL System". This system is published in the OGL Rulebooks. It is also described in specific roleplaying games such as in the Conan The Roleplaying Game or Lone Wolf; in these cases, the system was slightly modified to match the universe.