[Tagging] Terminology primary feature, main tag, etc..

[Peter Elderson]

I would avoid "primary key", because that is a term from database
management systems. It means the identifying attribute (Id) of an entity,
usually a unique identifier with an index (primary index), used to retrieve
records and to link the entity (table) to other tables. Something else
entirely.

Main key is better.

Further: the main key gives the type of object, the main tag gives a
category within that type of object. That is an important difference, in
documentation.

Feature tag, I think it means the tag that gives the object type (the main
key)  and the category within the object type (the value). So, equivalent
to main tag.
I think the term secondary tag(s) and secondary key(s) are often used for
the extra attributes of a feature, implying there should be a main tag
first, to give the secondary tags meaning.

Peter Elderson


Op ma 3 okt. 2022 om 12:40 schreef martianfreeloader <
martianfreeloader at posteo.net>:

> Thank you all for the many insightful replies to my question!
>
> What I've learnt so far:
>
> 1) A feature is something in the physical world. This is well documented
> in the wiki: https://wiki.openstreetmap.org/wiki/Features
>
> 2) There is no such thing as a "primary feature".
>
> 3) The terms "main key", "primary key" and "feature tag" are synonymous,
> except for the tag/key distinction.
>
> 4) None of the above terms is official OSM terminology.
>
> 5) None of these terms is well documented in the wiki.
>
> -------
>
> It looks like a couple of things would be good to get done:
>
> A) We should get rid of the term "primary feature" in the wiki page
> https://wiki.openstreetmap.org/wiki/Map_features
>
> B) It would be useful if we agree on *one* official term for "main key",
> "primary key" or "feature tag". (I think "primary key/tag" is the most
> popular one)
>
> C) We should document what we mean by this.
>
> ------
>
> Open questions:
> Q1) Which term should we choose as official term? ("main key"/"primary
> key"/"feature tag")
>
> Q2) Should one OSM object hold multiple "primary tags"? (ongoing
> discussion between Mateusz, Martin, Warin, Marc et al.)
>
>
>
> On 03/10/2022 12:16, Marc_marc wrote:
> > Le 03.10.22 à 10:47, Mateusz Konieczny via Tagging a écrit :
> >> there are cases where road is going in stream bed
> >
> > imho only one main feature/objet : the stream bed
> > and car use it, a bit like a bicycle uses a road.
> >
> > but we don't really have a secondary tag to say that
> > the stream bed is usable by a car... so we end up
> > describing this secondary use with a 2nd main tag...
> > this is not perfect
> >
> >
> >
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