This is the Licence for This Style Guide as well as for the whole Blender Core Documentation. You are kindly requested to produce any contribution to the Blender Documentation Project by using this License. If your contribution is outside Core documentation (as a tutorial, demo .blend file, images or animation) and you wish to use a more restrictive License you can use the Appendix E.
the source of the Open Content License is http://opencontent.org/opl.shtml. It is reported herebelow for easier reference.
OpenContent License (OPL)
Version 1.0, July 14, 1998.
This document outlines the principles underlying the OpenContent (OC)
movement and may be redistributed provided it remains unaltered.
For legal purposes, this document is the license under which
OpenContent is made available for use.
The original version of this document may be found at
http://opencontent.org/opl.shtml
LICENSE
Terms and Conditions for Copying, Distributing, and Modifying
Items other than copying, distributing, and modifying the Content
with which this license was distributed (such as using, etc.) are
outside the scope of this license.
1. You may copy and distribute exact replicas of the OpenContent
(OC) as you receive it, in any medium, provided that you conspicuously
and appropriately publish on each copy an appropriate copyright notice
and disclaimer of warranty; keep intact all the notices that refer to
this License and to the absence of any warranty; and give any other
recipients of the OC a copy of this License along with the OC. You may
at your option charge a fee for the media and/or handling involved in
creating a unique copy of the OC for use offline, you may at your
option offer instructional support for the OC in exchange for a fee,
or you may at your option offer warranty in exchange for a fee. You
may not charge a fee for the OC itself. You may not charge a fee
for the sole service of providing access to and/or use of the OC via
a network (e.g. the Internet), whether it be via the world wide web,
FTP, or any other method.
2. You may modify your copy or copies of the OpenContent or any portion
of it, thus forming works based on the Content, and distribute such
modifications or work under the terms of Section 1 above, provided that
you also meet all of these conditions:
a) You must cause the modified content to carry prominent notices
stating that you changed it, the exact nature and content of the
changes, and the date of any change.
b) You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the OC or any part
thereof, to be licensed as a whole at no charge to all third parties
under the terms of this License, unless otherwise permitted under
applicable Fair Use law.
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the OC, and
can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the OC, the distribution of the whole must be on the terms of this
License, whose permissions for other licensees extend to the entire
whole, and thus to each and every part regardless of who wrote it.
Exceptions are made to this requirement to release modified works
free of charge under this license only in compliance with Fair Use
law where applicable.
3. You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to copy,
distribute or modify the OC. These actions are prohibited by law
if you do not accept this License. Therefore, by distributing or
translating the OC, or by deriving works herefrom, you indicate
your acceptance of this License to do so, and all its terms and
conditions for copying, distributing or translating the OC.
NO WARRANTY
4. BECAUSE THE OPENCONTENT (OC) IS LICENSED FREE OF CHARGE, THERE
IS NO WARRANTY FOR THE OC, TO THE EXTENT PERMITTED BY APPLICABLE
LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS
AND/OR OTHER PARTIES PROVIDE THE OC "AS IS" WITHOUT WARRANTY OF
ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. THE ENTIRE RISK OF USE OF THE OC IS WITH YOU.
SHOULD THE OC PROVE FAULTY, INACCURATE, OR OTHERWISE UNACCEPTABLE
YOU ASSUME THE COST OF ALL NECESSARY REPAIR OR CORRECTION.
5. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
MIRROR AND/OR REDISTRIBUTE THE OC AS PERMITTED ABOVE, BE LIABLE
TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL
OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO
USE THE OC, EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED
OF THE POSSIBILITY OF SUCH DAMAGES.