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<p>Thanks Sebastiaan for looking at it! I'm not a lawyer neither,
but my understanding is that what PROJ is doing is re-licensing
(not to be confused with sub-licensing), which is disallowed by
almost every licenses I'm aware of, even the MIT license.
Repackaging the data in a different format does not erase the
creator copyright, in the same way that re-encoding a movie in a
different video codec does not erase the movie creator rights.
However the situation is not so problematic: it does not
necessarily force users to do an extra step, it depends on the
policy chosen by the project using PROJ (more on it below).<br>
</p>
<p>PROJ 6 and later are already complying with most EPSG
conditions: it does not modify the data, new data (e.g. IAU
data) are not attributed to EPSG. The main remaining condition
is to inform users about EPSG terms of use, and not give them
the impression that they are under MIT license. The approach can
be as below:</p>
<p>1) Put EPSG data in a separated directory or repository, with a
clear LICENSE file containing a copy of EPSG terms of use and a
link to the <a class="moz-txt-link-freetext" href="http://www.epsg.org/TermsOfUse.aspx">http://www.epsg.org/TermsOfUse.aspx</a> page.<br>
</p>
<p>2) Make the EPSG database optional (even if obviously strongly
recommended) for PROJ working.</p>
<p>3) Projects using PROJ have a choice:</p>
<ul>
<li>They can bundle the EPSG database directly in their software
if it is okay for them to inform users about EPSG terms of use
when they download the binary. Many projects show the license
on the web page where users download the software, and it is
not uncommon that there is more than one license. In my
understanding if that page said clearly the licenses of all
material in the software (including EPSG terms of use), it is
okay.</li>
<li>Alternatively, some projects refuse to add any licenses
stricter than their own license. This is the case of Apache
foundation, where even LGPL code are not accepted in Apache
projects. Apache projects like NetBeans workaround this
problem with a popup windows shown the first time that the
application is started, which offer to download the material
under non-Apache license. It is only one click for the user,
and is required only for projects who don't want to bundle
EPSG terms of use in their software from the root.</li>
</ul>
<p>So for example QGIS could offer two downloads: a 100% free
version where downloading EPSG database would be a separated
step, and maybe (if the foundation driving the QGIS project is
fine with that) an alternative download with EPSG database
bundled in it, but with also the EPSG terms of use "bundled"
with the license of that version.</p>
<p>Having material under a stricter license is not uncommon in
open source project. Apache projects are facing this situation
many times and developed different ways to address that, Linux
distributions have "non-free" repository (e.g. for proprietary
video drivers), etc. Furthermore putting the data in a separated
directory is desirable even if we didn't had licensing issue
because the main source of CRS definitions is currently EPSG,
but ISO is also working on that. So in the future we may have 2
sources of definitions, probably with different tradeoff to
chose.<br>
</p>
<p> Martin</p>
<p><br>
</p>
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