What is a guru license, and what is a non-guru license?
A guru license is a license where a guru can change the terms of the
license according to his whims.
You can recognise the existense of a guru to the presence of the
following lines :
CC-BY-SA 3.0 : "either this or a later license version".
GFDL : "The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time" (but you can
opt-out of the guru if you remove "or any later version" from your
licensing statement).
Conversely, CC-BY-SA 1.0 does not contain any such revision mechanism.
To the contrary of the other CC licenses, the following sentence at
the end of the license : "This License constitutes the entire
agreement between the parties with respect to the Work licensed here.
There are no understandings, agreements or representations with
respect to the Work not specified here", is true to its meaning.
Philosophically, I don't see why I should choose for my created
contents, or recommend to other creators to choose a guru-license.
Depending on the whims of a guru amounts to the servitude denounced by
Étienne de La Boétie (1530-1563) in his 1548 essay "Discourse on
voluntary servitude"(1)
CC-BY-SA-Guru is CC-BY-SA 3.0
CC-BY-SA-NonGuru is CC-BY-SA 1.0
GFDL-Guru is "GFDL + version number or any later version"
GDFL-NonGuru is "GFDL version + version number" practically that means
"GFDL 1.2" (GFDL 1.3 has to be avoided because of its transfer
mechanism to Creative Commons)
Both the CC-BY-SA 1.0, and the strict GFDL 1.2 must be included in the
upload wizard.
The uploading tutorial should explain beginners the difference between
these licenses and the other licenses, enabling them to choose in full
knowledge of the facts.
(1)
http://en.wikisource.org/wiki/Discourse_on_Voluntary_Servitude