[OSM-talk] Poll: Syntax for restrictions with conditions

Tobias Knerr osm at tobias-knerr.de
Tue Jul 28 17:05:27 BST 2009


Hi, some of you might know my proposal

http://wiki.openstreetmap.org/wiki/Proposed_features/Extended_conditions_for_access_tags

or its predecessor, "Conditions for access tags". The proposal presents
the idea of adding conditions to existing keys (such as maxspeed, access
...). A tag with conditions will only have an effect if all conditions
are valid. Something like this is necessary to describe many traffic
restrictions encountered in reality: restrictions only valid on wet
roads, at night, ...

The original proposal suggested using colons (":") to separate
conditions from the base key and each other. However, recently discussed
tagging concepts as well as the extensions introduced after the first
proposal have demonstrated some problems with that syntax. Most
importantly, colons
* are used by the {{tag|opening_hours}} syntax which imo would be a good
choice for timed restrictions
* are used as a namespacing solution and some recent ideas (such as
left/right ordering) might also use colons as a separator
* are used in situations where the order of key components matters. The
order of conditions, however, is semantically irrelevant.
Therefore, angle brackets ("[ ]") have been suggested on talk-de as an
alternative to using colons.

Please state your opinion in the poll on the proposal's wiki page:
Which syntax do you prefer?

Tobias Knerr




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