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<p>Hello Ben</p>
<div class="moz-cite-prefix">Le 23/03/2026 à 21:21, Ben Griffin via
PROJ a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CF5A36B2-D6A2-454C-979A-43DF17B6672A@redsnapper.net">
<pre wrap="" class="moz-quote-pre">As I understand it - and I am happy to be corrected, it appears that you are confirming that there is not (yet) an
agreed standard as to what a DGGS should be in ISO terms.</pre>
</blockquote>
<p align="justify">There is an ISO standard for DGGS, which is ISO
19170-1 at <a class="moz-txt-link-freetext" href="https://www.iso.org/standard/32588.html">https://www.iso.org/standard/32588.html</a>. The same
standard is available for free on the OGC web site at
<a class="moz-txt-link-freetext" href="https://docs.ogc.org/as/20-040r3/20-040r3.html">https://docs.ogc.org/as/20-040r3/20-040r3.html</a>. This is a joint
OGC/ISO standard, like ISO 19111 which is identical to "OGC Topic
2" except for the cover and formatting.</p>
<p align="justify">However, PROJ's C++ API is derived from ISO
19111, and that standard has not been designed for DGGS. There is
no plan to adapt ISO 19111 to DGGS, at least in the current ISO
19111 revision work. If PROJ wanted to introduce an API for the
referencing part of DGGS, ISO 19112 may be a better model. I just
saw that ISO 19170 references ISO 19112 in its list of normative
references, so it seems that there is some agreement about its
pertinence. We have used ISO 19112 years ago as an API for
Military Grid Reference System (MGRS) and it worked well. My
impression is that the use of ISO 19112 for modelling an API for
DGGS during the OGC Testbed this year gave good results as well.</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:CF5A36B2-D6A2-454C-979A-43DF17B6672A@redsnapper.net">
<pre wrap="" class="moz-quote-pre">My work - Hex9 - straddles both standards cleanly:
- The projection (continuous CRS) — ISO 19111
- The addressing system (H9 cell hierarchy) — ISO 19112</pre>
</blockquote>
<p>Yes, I think that this is the way that it has been implemented in
at least part of the OGC Testbed. The Testbed reports should be
published later this year normally, maybe in autumn.</p>
<p> Martin</p>
<p><br>
</p>
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