View source for Modifying the CC licenses

===CC policy===
CC recognizes that we cannot control or prohibit separate agreements or understandings outside of CC's standard license terms. After all, CC is not a party to the license – it is an agreement between the licensor and licensee. We can, however, insist that CC trademarks not be used in connection separate agreements, understandings, and interpretations that create unwanted friction.

'''CC has the following guidelines for modifying or supplementing its licenses:'''

#'''If you make a change to the legal terms of the license, ''you may no longer call it a Creative Commons license.'''''
#'''If you place an extra contractual restriction on use of the licensed work that has the effect of limiting or further conditioning the permissions granted to the public under the standard CC license, ''you may not use the CC trademarks in connection with your license.''''' These extra contractual restrictions often appear in terms of use on websites where CC-licensed content is hosted, or as part of terms for downloading CC-licensed content.

::*Example of impermissible extra restriction= imposing terms of use that prohibit downloading the work or terms of use that are designed to explain how the license works in a way that contradicts the plain meaning of the standard terms, such as dictating that the definition of NonCommercial hinges on the type of reuser as opposed to the type of use
:::-but it is permissible to have separate trademark guidelines that dictate how a logo may be used in connection with the work or impose terms of use that restrict access of the site to minors pursuant to Internet regulations 
::*Example of impermissible extra restriction = imposing terms of use that prohibit sharing of the work in certain formats 
:::-but it is permissible to distribute the work in a format that is not easily shared or to put content behind a paywall
::*Example of impermissible extra restriction = imposing more elaborate attribution requirements via terms of use  
:::-but it is permissible to impose terms of use that have the effect of increasing (or removing the conditions on) the permissions granted to the public under the standard terms, such as waiving the attribution condition or allowing translations of an ND-licensed work (see [http://wiki.creativecommons.org/CCPlus CC+])

CC does recognize that providing clarification can make sense intuitively, and is arguably useful in a few limited circumstances, but only when doing so:
*is consistent with, and not contrary to, the terms of the license, and does not alter the usage permissions or alter the conditions imposed
*does ‘’’not’’’ impose any requirement on a particular class of users that they contact the licensor in advance for permissions the license has already granted
*does ‘’’not’’’ otherwise increase transaction costs for any potential licensee

=== Rationale for the CC policy: ‘‘the beauty of standardization’’ ===
The above guidelines are designed to preserve the underlying principles and benefits of public licensing for licensors and licensees, by reducing conflicts and confusion that may ensue. One of the fundamental design principles of CC licensing is granting permission to the public in advance, thereby reducing transaction costs and facilitating reuse. CC licenses achieve this result through terms and conditions that are ‘’standard,’’ meaning the same terms and conditions apply for all content licensed under a particular CC license. The result is reduced friction for creators who want to allow certain reuses without negotiating and granting lots of individual permissions, and for reusers who want to make use of that content with minimal hassle.