[Proj] ICSM (Australia) transformation file licensing

Sebastiaan Couwenberg sebastic at xs4all.nl
Wed Jan 18 13:31:14 EST 2017

On 01/18/2017 09:17 AM, Martin Desruisseaux wrote:
> 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.

I've tried to have a discussion with OGC about the issues with their
licensing of standards and their implementation in Free Software
projects several times in the past, all I every got was a reply that
they would discuss it internally and never heard from them again.

This lead me to give up on ever making progress on this issue, the core
of geospatial software is simply non-free and the organisations involved
have not shown willingness to work with the community to resolve that.

The authors of the AC codec made a similar decision to not allow
modification, which subsequently made its use in LASzip problematic
enough that it cannot be included in Linux distributions and users of
LiDAR projects are forced to maintain custom builds because
distributions cannot provide support the LAZ format.

> 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).

Open Source implementations of Open Standards help them thrive,
licensing Open Standards in ways that make them incompatible with open
source projects hinder adoption of the standards.

PROJ.4 using the EPSG name is indeed a problem that should be fixed.

> 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.

While I understand the motivations of EPSG, just like I understand them
of the Dutch Kadaster with whom I've had the same discussion after they
published their NTv2 correction grids, limiting modification is simply
incompatible with Free Software licenses.

The right to make modifications is simply essential to Free Software. As
Greg also mentioned, in practice no one wants to make use of this right
because that would make their implementation incompatible with the rest
of the world beating the purpose of standards.

> 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.

"annoying" is not the right word. Limiting modification simply means
that the grid shift files cannot be included in open source projects
using Free Software licenses ensuring it cannot be working out-of-the
box. The users are forced to retrieve and install the grids themselves.

I'm my opinion, all organisations publishing national grid shift files
should consider they're stance on limiting modifications. The French and
New Zealand grids are public domain, and the Hungarian grid is GPL-2+.
They apparently consider compatibility with Free Software projects more
important than limiting modification.

Kind Regards,


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