the OGL, and products based on the SRD may still be released under the OGL alone. Criticisms Unlike the OGL, the d20STL is revocable and is controlled by Wizards of the Coast. Wizards of the Coast has the ability to alter the d20 System Trademark License at will, and gives a short, 30-day "cure period" to rectify any issues with the license before termination. These changes apply retroactively to all material published under the d20 System Trademark License. Book of Erotic Fantasy When gaming company Valar Project attempted to publish the d20 Book of Erotic Fantasy (BoEF), which focused on sexual content, Wizards of the Coast altered the d20 System Trademark License in advance of publication of BoEF by adding a "quality standards" provision that required publishers to comply with "community standards of decency." This subsequently prevented the book's publication under the d20STL. Wizards of the Coast said this was done to protect its d20 System trademark. The Book of Erotic Fantasy was subsequently published without the d20 System trademark under the OGL. Other books subsequently published under similar circumstances include Skirmisher Publishing's Nuisances, which includes on its cover the disclaimer "Warning: intended for mature readers only." The same round of changes to the license also limited the size at which the text "Requires the use of the Dungeons & Dragons Player's Handbook, Third Edition, published by Wizards of the Coast" (which is required to appear on the front or back cover of most fantasy d20 System products) could be printed, and prohibited making part of it larger than the rest. Other criticisms Criticism is also levied at the conditions for termination of the d20 System Trademark License through a breach of its terms. The license requires that, upon breach of the terms of the d20STL which includes any subsequent modifications of the license after publication of a work using the d20 System trademark, all inventory and marketing material must be destroyed. Adhering to the breach conditions is an onerous task for smaller game companies. The mere threat of this condition being imposed was a huge blow to the now defunct d20 System publisher Fast Forward Entertainment, which had released several books that used non-open Wizards of the Coast content. Other criticism is concerned with the part of the d20 System Trademark License which defines "Open Game Content" to include game mechanics, and purports to license it. It is generally