[OSM-talk] Inheritance of roles in nested relations
frederik at remote.org
Sat Dec 20 22:33:25 GMT 2008
Hugh Barnes wrote:
> To provide clear guidance for clients, because as you said — and I think
> is right, though I can't currently think of examples — this inheritance
> is not always desirable. Also, component=yes prevents someone
> deleting something that looks useless on its own.
If you try to delete something that is part of a relation, either your
editor will ask you whether you want to remove it from the relation, or
it won't and get an error back from the API.
I maintain that it is not necessary to explicitly tag the parent or
children as the exact meaning can always be derived from the context;
but then again a little redundancy is not bad, makes it easier to spot
Be aware however that there is some tagging ambiguity here, for example:
Bus route relation
-> contains many
type "X" relations
-> each of which contains many
Now the type "X" relation could be a grouping of ways into superways
(someone collected all parts making up Oxford St into one relation, the
bus goes down the length of Oxford St, so you use that relation to route
your bus over). In that case, "X" would probably be tagged with usual
The type "X" relation could also be a sub-structure relation of the kind
you're talking about, in which case you would expect the parent/child
tagging scheme you were talking about.
It's all a bit murky but I presume we'll get it sorted within a few
Frederik Ramm ## eMail frederik at remote.org ## N49°00'09" E008°23'33"
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