[Proj] ICSM (Australia) transformation file licensing

Martin Desruisseaux martin.desruisseaux at geomatys.com
Wed Jan 18 03:17:07 EST 2017

Le 18/01/2017 à 15:33, Sebastiaan Couwenberg a écrit :

> Please don't disallow modification of the correction values like EPSG
> and many other national grids following their lead, those terms are
> incompatible with the GPL-2+.
Well, there is discussion at OGC about "open standard" versus "open
source". A summary is available in the "OGC API white paper" at [1].
Chapter 5 lists criterion similar to Open Source software, but
intentionally excludes from that list the freedom to modify the standard.

Open Source and Open Standard have different goals. The purpose of a
standard (even open) is compromised if anyone is allowed to modify it.
Of course restrictions like the EPSG terms of use are annoying for open
source licenses like GPL or Apache, but consequences of allowing
departure can be worst. The mess about axis order is an example.
(Actually the problem is not that much that some software change the
axis order, but that they are still using the "EPSG" name for their
modified CRS).

EPSG terms of use try to find a compromise by actually allowing some
modifications, provided that they preserve numerical equivalence. If
numerical equivalence is broken, then the modified CRS shall not be
named "EPSG". It can be a safety issue in transportation and other
domains if someone though that a coordinate was given in the "EPSG:4326"
CRS while actually it was given in "MyOwnTasteOfEPSG:4326" CRS. It seems
to me that the same issue applies to datum grid shift files and other
data published by authoritative agencies.

I would like to stress out that above does not forbid all modifications.
Some modifications are okay if they either preserve numerical
equivalence or make very clear (by using a different name among others)
that the modified data are not any more compliant with the standard. The
golden rule is to not mislead the users.

I agree that this is annoying for open source software, but we can
workaround by putting the data in a "non-free" (or other name)
repository for making clear that those data are subject to different
licensing conditions than the GPL ones. If forcing the users to download
two bundles is considered too annoying, I think it is still possible to
have a single bundle if the data terms of use are shown together with
the GPL license when the user get Proj.4.



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