On Mon, Mar 24, 2014 at 10:38:08PM +0100, fly wrote: > On 24.03.2014 20:45, Richard Z. wrote: > > On Mon, Mar 24, 2014 at 11:02:35AM -0300, Fernando Trebien wrote: > >> On Mon, Mar 24, 2014 at 10:27 AM, Friedrich Volkmann <b...@volki.at> wrote: > > As it might be even hard to define the ground level (we just have a > discussion on talk-de@ about houses built on slops), I would never say > that an negative layer value is an indicator/synonym for underground. > > >> Again, no mention in the wiki > >> (http://wiki.openstreetmap.org/wiki/Key:layer) to negative layer > >> values being used to represent the idea of underground. > > > > not an explicit mention, but if there is an object X1 with implicit layer=0, > > with no level or location tags, and another object X2 with a layer=-1 than > > there are not too many possibilities where to find X2. It could be > > underground > > or it could be under a large overhanging rock. Both should have explicit > > tags to clarify the situation. > > > > > >>> No, except for underground rivers. They do exist in karst regions... > > > > we need a way to tag underground rivers and lakes. layer=-1 itself is not > > sufficient, we need additional tags. Perhaps tunnel=cave but this would > > only describe part of those phenomena. > > How about location=underground ?
seems good to me. > covered=yes is another useful tag (eg your overhanging rock) "covered" is already complicated enough and this might be too much of stretching the original idea. Richard _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
