[OSM-talk] Tagging schema

James Livingston doctau at mac.com
Tue Oct 6 13:35:17 BST 2009

On 05/10/2009, at 7:54 PM, David Earl wrote:
> * Three new primitives, tagkey for describing the k part of tags,
> tagvalue for the v part of tags and tagdescription separated off to
> allow for multiple descriptions in multiple languages without having  
> to
> download all the data for languages you're not interested in.  
> ("tagkey"
> etc can be anything we want, don't get too hung up on the  
> terminology, I
> just use it for didactic purposes).

I'd been thinking something along these lines for a while, due to  
having used a similar system at an old job. There everything in the  
database was described my metadata in The Dictionary, and The  
Dictionary lived in the database too. Essentially, we'd just allow the  
tagging of tags (keys and values) in the same way that we tag nodes,  
ways and relations.

I think being able to add arbitrary metadata to tags would be handy,  
because you can come up with cool new things. For example, you could  
tag the proposed incline=up tag with "edit:reverse_way=value_flip" or  
similar, which says the value needs to be flipped if the way is  
reversed. If an editor knew what to do for that tag it could do it  
automatically, and if it didn't it could present a warning to the user.

Control would be an issue though, as someone accidentally or  
maliciously breaking tag metadata could really screw things up, if  
editor and renders went straight off it rather than "verified" copied.

> (d) the meaning of newly introduced or changed tags goes along with

> them, so that the intention is described to others.

I can see things getting ickier than they are now if you can just go  
around adding new shop= values, without having some prior discussion  
to what it means. If I saw a suggested option in an editor, I would  
generally assume that there is some agreement as to what it is  
supposed to mean.

More information about the talk mailing list