You'll want to get down to millimeter.

For one reason...There are already tons of public LIDAR datasets with point data down to millimeter.
I've even seen monuments and public art sculptures that have LIDAR datasets down to millimeter precision using WGS84 base references. (think knowing the coordinates for George Washington's left nostril on Mount Rushmore against trilateration references of WGS84 ... crazy I know, but its out there)

Having it all queryable in Wikidata ?  hmmm... not for me, other data catalogs and GIS systems handle that job.
But having the datasets linked etc. to spatial references ?   You'll want to ensure that folks can populate against a spatial reference property like the City of Georgetown example link above that gives:
Spatial Reference:

EPSG 2277

My thoughts,

On Wed, Aug 30, 2017 at 4:19 PM Jan Macura <> wrote:

On 30 August 2017 at 22:29, Stas Malyshev <> wrote:
True, but this probably won't be kept up-to-date and most likely would
be useless for Wikidata users since random very precise data can not be
relied on unless there's a guarantee certain set of data (e.g. all
observatories) have the same accuracy and it is kept up-to-date.
Like in all the wiki-world, this should be guaranteed through the reference claim, shouldn't it?
I think we should at least limit it to specified precision (not the case
today) but maybe even more in case precision is too high. I don't think
anything beyond 1m is really useful - please provide use cases if you
think otherwise.
I can't think of anything really useful right now... What I'm afraid of is creating fake grids like it happened in DBpedia with too much rounding (see [1], p. 44/45). Maybe with 1 m precision it won't happen today, but it might in the future for very POI-dense areas.. (might it?)

Best regards
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