<P> An alternative is for copyright holders to issue a licence which irrevocably grants as many rights as possible to the general public . Real public domain makes licenses unnecessary, as no owner / author is required to grant permission ("Permission culture"). There are multiple licenses which aim to release works into the public domain . In 2000 the WTFPL was released as a public domain like software license . In 2009 the Creative commons released the CC0, which was created for compatibility with law domains which have no concept of dedicating into public domain . This is achieved by a public domain waiver statement and a fall - back all - permissive license, in case the waiver is not possible . The Unlicense, published around 2010, has a focus on an Anti-copyright message . The Unlicense offers a public domain waiver text with a fall - back public domain - like license inspired by permissive licenses but without attribution . </P> <P> In October 2014 the Open Knowledge Foundation recommends the Creative Commons CC0 license to dedicate content to the public domain, and the Open Data Commons Public Domain Dedication and License (PDDL) for data . </P> <P> In most countries the term of rights for patents is 20 years, after which the invention becomes part of the public domain . In the United States, the contents of patents are considered valid and enforceable for 20 years from the date of filing within the United States or 20 years from the earliest date of filing if under 35 USC 120, 121, or 365 (c). However, the text and any illustration within a patent, provided the illustrations are essentially line drawings and do not in any substantive way reflect the "personality" of the person drawing them, are not subject to copyright protection . This is separate from the patent rights just mentioned . </P> <P> A trademark registration may remain in force indefinitely, or expire without specific regard to its age . For a trademark registration to remain valid, the owner must continue to use it . In some circumstances, such as disuse, failure to assert trademark rights, or common usage by the public without regard for its intended use, it could become generic, and therefore part of the public domain . </P>

When does a patent enter the public domain
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