All article revisions added to Memory Alpha on or after 1 December 2015 are considered to be released under version 4.0 of the Creative Commons Attribution/Non-Commercial license (CC-BY-NC 4.0). If this revision is a "derivative work" of a prior article revision, it is considered to be re-licensed from its previous license to CC-BY-NC 4.0 unless the prior license expressly disallows such re-licensing. In this case, the new article revision is licensed under the same license as the previous revision.
All article revisions added to Memory Alpha before 1 December 2015 are considered to be released under an earlier version of the CC-BY-NC license, namely:
version 2.5, if added to Memory Alpha between 3 November 2005 and 30 November 2015
version 2.0, if added to Memory Alpha between 19 June 2004 and 2 November 2005
version 1.0, if added to Memory Alpha between 15 January 2004 and 18 June 2004
Revisions added before 15 January 2004 were originally licensed under a version of the GFDL.
In case of differences between two or more involved versions of the CC-BY-NC license, licensees need to comply with the more restrictive wording.
