[PROJ] Is CRS84 a datum ensemble?

[Luí­s Moreira de Sousa]

Hi Even,

thank you for the reply. The statement "No distinction is made between the original and subsequent" leads me instead to understand CRS84 as strictly referring to the original datum. But the OGC registry is not normative, as far as I know.

In the standard itself that interpretation is not given. There the WGS 84 is referenced more broadly. This is essentially the source of my doubt.

Regards.

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------- Original Message -------
On Thursday, August 18th, 2022 at 3:07 PM, Even Rouault <even.rouault at spatialys.com> wrote:

> Luís,
>
> http://www.opengis.net/def/crs/OGC/1.3/CRS84 is the verbose definition of OGC CRS84.
>
> It uses the EPSG:6326 datum (now modeled as a datum ensemble in EPSG v10 database releases).
>
> The following remarks in the definition makes it clear that the intent if to be based on the datum ensemble rather than a particular realization:
>
> <gml:remarks>
> EPSG::6326 has been the then current realization. No distinction is made between the original and subsequent (G730, G873, G1150, G1674 and G1762) WGS 84 frames. Since 1997, WGS 84 has been maintained within 10cm of the then current ITRF.
> </gml:remarks>
>
> For all purposes, OGC:CRS84 is identical to EPSG:4326 but the axis order.
>
> Even
>
> Le 18/08/2022 à 14:59, Luí s Moreira de Sousa via PROJ a écrit :
>
>> Hi all,
>>
>> this is not a Proj question per se, but possibly relevant to the library. The specification is not clear, whether it refers to the datum ensemble or to a particular datum (Transit?). Any insight on the intention of the OGC in this regard?
>>
>> Thank you.
>>
>> --
>> Luís
>>
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>
> --
> http://www.spatialys.com
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