About the statement about Debian and the CC licenses on Wikipedia.

[Charles Plessy <plessy@debian.org>]

Dear FTP team and everybody,

The Wikipedia page about Creative Commons mentions:

    http://en.wikipedia.org/wiki/Creative_Commons#Debian

    The maintainers of Debian, a GNU and Linux distribution known for its rigid
    adherence to a particular definition of software freedom,[citation needed]
    rejected the Creative Commons Attribution License prior to version 3 as
    incompatible with the Debian Free Software Guidelines (DFSG) due to the
    license's anti-DRM provisions (which might, due to ambiguity, be covering more
    than DRM) and its requirement that downstream users remove an author's credit
    upon request from the author.[49] However, version 3.0 of the Creative Commons
    licenses addressed these concerns[50] and is considered to be compatible with
    the DFSG.[51]

    [49] Evan Prodromou (3 April 2005). "Summary of Creative Commons 2.0
    Licenses". debian-legal (mailing list).
    http://evan.prodromou.name/ccsummary/ccsummary.html

    [50] Garlick, Mia (2007-02-23). "Version 3.0 Launched". Creative Commons.
    Retrieved 2007-07-05.
    http://creativecommons.org/weblog/entry/7249

    [51] "The DFSG and Software Licenses - Creative Commons Share-Alike (CC-SA)
    v3.0". Debian Wiki. Retrieved 2009-03-16.
    https://wiki.debian.org/DFSGLicenses#CreativeCommonsShare-Alike.28CC-SA.29v3.0

However, the reference [50] mentions that not all of Debian's concerns about
DRMs were addressed.

    As part of discussions with Debian, it was proposed to allow the release of
    CC-licensed works under DRM by licensees on certain conditions — what was known
    as the “parallel distribution language” but this has not been included as part
    of Version 3.0 of the CC licenses.

Here are the clauses about DRMs in versions 2.5 and 3.0 of the CC-BY licenses
respectively.

    You may not distribute, publicly display, publicly perform, or publicly
    digitally perform the Work with any technological measures that control access
    or use of the Work in a manner inconsistent with the terms of this License
    Agreement.

    When You Distribute or Publicly Perform the Work, You may not impose any
    effective technological measures on the Work that restrict the ability of a
    recipient of the Work from You to exercise the rights granted to that recipient
    under the terms of the License.

Here are the clauses in version 2.5 and 3.0 about credit.

    If You create a Collective Work, upon notice from any Licensor You must, to
    the extent practicable, remove from the Collective Work any credit as required
    by clause 4(b), as requested. If You create a Derivative Work, upon notice from
    any Licensor You must, to the extent practicable, remove from the Derivative
    Work any credit as required by clause 4(b), as requested. 

    If You create a Collection, upon notice from any Licensor You must, to the
    extent practicable, remove from the Collection any credit as required by
    Section 4(b), as requested. If You create an Adaptation, upon notice from any
    Licensor You must, to the extent practicable, remove from the Adaptation any
    credit as required by Section 4(b), as requested.

I do not see key differences between CC-BY 2.5 and 3.0 on these matters.

Could you tell what was the key change that made CC-BY 3.0 acceptable for Debian ?

Alternatively, could you confirm that the information in Wikipedia is wrong ?
I will then correct it by deleting the paragraph about Debian.

Have a nice week-end,

-- 
Charles Plessy
Tsurumi, Kanagawa, Japan