Unless otherwise indicated, text and images contributed by AAPG is copyright of AAPG and is formally licensed to the public under the Creative Commons Attribution-Sharealike 3.0 Unported License (CCcasing collar-BY-SA).
Any new text contributed to this wiki is copyrighted automatically (under the Berne Convention) by the contributors and is similarly licensed to the public under Creative Commons Attribution-Sharealike 3.0 Unported License (CCcasing collar-BY-SA).
The CCcasing collar-BY-SA license
The CCcasing collar-BY-SA license grants free access to our content in the same sense that free software is licensed freely. Content can be copied, modified, and redistributed if and only if the copied version is made available on the same terms to others and acknowledgment of the authors of the wiki article used is included (a link back to the article satisfies the attribution requirement). Copied Encyclopedia of Mathematics content will therefore remain free under appropriate license and can continue to be used by anyone subject to certain restrictions, most of which aim to ensure that freedom. This principle is known as copyleft in contrast to typical copyright licenses.
Please be aware that content of this wiki is covered by disclaimers.
For any reuse or distribution, you must make clear to others the license terms of this work. The best way to do this is with a link to this wiki page.
Contributors' rights and obligations
If you contribute text to this wiki, you thereby license it to the public for reuse under CCcasing collar-BY-SA. Non-text media may be contributed under a variety of different open licenses that support the general goal of allowing unrestricted re-use and re-distribution. See Guidelines for images and other media files, below.
If you want to import text that you have found elsewhere or that you have co-authored with others, you can only do so if it is available under terms that are compatible with the CCcasing collar-BY-SA license. If you are the sole author of the material, you must license it under both CCcasing collar-BY-SA.
If the material, text or media, has been previously published and you wish to donate it to the wiki under appropriate license, you will need to verify copyright permission.
You retain copyright to materials you contribute to the wiki. Copyright is never transferred to AAPG. You can later republish and relicense them in any way you like. However, you can never retract or alter the license for copies of materials that you place here.
Guidelines for images and other media
Images, photographs, video and sound files, like written works, are subject to copyright. Someone holds the copyright unless they have been explicitly placed in the public domain. Images, video and sound files on the internet need to be licensed directly from the copyright holder or someone able to license on their behalf. In some cases, fair use guidelines may allow them to be used irrespective of any copyright claims; see Non-free content for more.
Image description pages must be tagged with a special tag to indicate the legal status of the images, as described at Image copyright tags. Untagged or incorrectly-tagged images will be deleted.
Contributors who repeatedly post copyrighted material despite appropriate warnings may be blocked from editing by any administrator to prevent further problems.
If you suspect a copyright violation, you should at least bring up the issue on that page's discussion page. Others can then examine the situation and take action if needed.
If a page contains material which infringes copyright, that material – and the whole page, if there is no other material present – should be removed. See Copyright violations for more information, and Copyright problems for detailed instructions
Works by the United States Federal Government
Works produced by employees of the United States federal government in the scope of their employment are public domain by statute in the United States (though they may be protected by copyright outside the US). The employee must have made the work as part of his/her duties.
However, not every work republished by the US government falls into this category. The US government can own copyrights that are assigned to it by others, for example, works created by contractors.
These guidelines were originally based on the excellent model at the Encyclopedia of Mathematics.