On Mon, 18 Jul 2011 16:05:29 +0100, Ed Loach wrote:
Relations
without
members can be used intentionally,

Can you give an example, please? Because I've tried and failed to
think of any. Perhaps I'm just getting hung up on the name "relation"
as something which groups its related members in some way defined by
the relation's tags (while not being used as a category).

For example in Prague there is relation for transport network which contain empty relation for some tram lines - those are not operational currently due to some constructions, but once these constructions are finished, they can be easily restored to previous state (just dig up some older version of the relation from history, check it and save it)

There are quite rare uses for empty relation (but being a member of other relation) and mostly these uses are temporary. Since if you download some data by some given bbox, you will get that empty relation (along with some other data).

But relations that contain no members and themselves are not members of nay other relation are "invisible" - they are not contained in any bounding box, they do not affect rendering, routing or anything and basically you can download them only by ID (or parse them from planet dump). So these are basically useless ....

Martin

_______________________________________________
talk mailing list
talk@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk

Reply via email to