[OSM-talk] [tagging] Feature Proposal - RFC - Properties for Tags

Andrew Chadwick (mailing lists) andrewc-email-lists at piffle.org
Thu Jan 1 22:31:45 GMT 2009

Sebastian Hohmann wrote:
> http://wiki.openstreetmap.org/index.php/Proposed_features/Properties_for_Tags

Possibly a little overcomplex; it sounds like you're trying to introduce 
some form of metatagging - tags about other tags - when limited 
metatagging already exists, of a sort (source:name=*, for example).

Stylistically, could existing colon "syntax" be used for what you're 
doing here? I've jotted down some stuff about forms I've seen elsewhere 
at <URL: http://wiki.openstreetmap.org/wiki/Any_tags_you_like#Syntactic_ 
conventions_for_new_tags >, see if you agree. It's admittedly not much 
of a formally defined syntax; could it do with being formalised?

There are some corner cases it would be Quite Nice to address with a 
generative / metatag scheme: my own bugbears are

   * hour_on and hour_off for specific modes of transport

   * left-side and right-side for (UK:) pavements (US:) sidewalks and
     bicycle paths.

The .only. and .except. stuff sounds like you're trying to mix 
predicates and logical inference into this all. Which might be nice, but 
this proposal will needs a better explanation of what you're trying to 
achieve here in order to sell it. I'd personally like parsing of tag 
keys to be simple, and not context-sensitive. Couldn't you do 
conditionality in a more future-proof way with S-exps or somesuch in the 
tag's value? (Kidding, kidding! I mean XML! D: )

I don't like the notion of the dots sometimes representing simple 
hierarchy and sometimes representing logic depending on what atoms are used.

Andrew Chadwick

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