[Tagging] Let's get (quite) rid of units and their multiples in OSM values

Tobias Knerr osm at tobias-knerr.de
Fri Jul 27 20:21:01 UTC 2018

On 26.07.2018 21:26, François Lacombe wrote:
> Then store voltage=400000 is far way better but harder to be read by
> humans also.

I currently prefer explicit units in the database because they document
the mapper's intent and avoid ambiguity.

Defaults aren't always obvious. For example, people mapping pipelines
have documented millimetres as the default for diameter=*, but it seems
tree mappers haven't gotten the memo and (reasonably) assume it's
defaulting to metres like height=*, width=* or circumference=*.

When a value is actually signposted on the ground, it's most likely
preferable to use the original unit and avoid conversions. Apart from
that particular case, I can see some benefits of your suggestion – _if_
you can convince the community to reliably agree on how unit-less values
are interpreted.

> https://wiki.openstreetmap.org/wiki/Map_Features/Units doesn't help
> regarding such issues.

It helps by providing data consumers with information they need to
support both explicit and implicit units. Some have gotten around to
implementing that feature, others haven't yet – but in principle, it
seems entirely possible to support queries like [voltage>20 kV], to use
your example.

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