[Tagging] Feature Proposals - RFC for multiple features - Education Reform - Magnetic Levitation Trains

Tobias Knerr osm at tobias-knerr.de
Sun Sep 17 08:52:09 UTC 2017


On 17.09.2017 07:54, Erkin Alp Güney wrote:
> This brings education key instead of amenity=school.

In my opinion, and speaking broadly, the job of the OSM tagging system
is to answer two questions:

- What kind of feature is this?
- What properties does this feature have?

The first question can usually be answered by a single word, such as
"university" or "driving school". The second is more naturally answered
with key-value pairs: The "name" is "Foobar University", the "website"
is "http://example.com" and so on.

So while our key-value tags lend themselves well to the second job, they
are a bit of an awkward fit for the first job. We need to put something
in the key even though it does not add any meaningful information. An
education=university would not be any different from an
amenity=university – all the information is already there in the value.

My preferred response to this situation is to minimize the significance
and required brain space for this vestigial key. If we were to reform
the tagging system, my ideal solution would be a "type"/"thing"/"class"
key that is used for the main tag of all features. Other than this
unlikely step, the next best solution is continued use of amenity as a
catch-all for most features.

Contrary to this, some mappers (and your proposal) prefer to use the
superfluous key as a makeshift category system. I feel that's the wrong
way to go, though: How to best group features into categories depends on
the application you have in mind, and providing a categorization is not
any more the tagging system's job than making rendering style decisions
is. OSM data tells you that there is an education ministry in that
location. Whether that feature is filed under the "education", "office"
or "government" heading is an application developer's responsibility,
and should be of no concern for the OSM data model.

tl;dr: Keys are not categories.

Tobias



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