On Tue, Oct 12, 2010 at 12:11 PM, M∡rtin Koppenhoefer <[email protected]> wrote: > 2010/10/12 Nathan Edgars II <[email protected]>: >> On Tue, Oct 12, 2010 at 11:26 AM, Pieren <[email protected]> wrote: >>> "layer" is just saying what is on the top when two objects/lines are >>> crossing each other. If you have only one element, the layer tag is really >>> optionnal (this until someone is tracing what is below). >> Even if you have two elements, it's obvious which is above the other >> if only one is bridge=* or tunnel=*. The purpose of the layer tag is >> to resolve ambiguities when two above-ground or two below-ground >> features cross. > > no, the layer tag is to map the stacking order on crossing objects. It > is not only for situations that you consider "ambigous" but it is for > all situations where different objects cross. What's the problem in > using a layer-tag together with a bridge or tunnel? Why would you want > to "save" tags?
Why would you want to force useless tags? I have no objection to adding correct but unnecessary layer tags, but they're optional. > >>> And we can also put the layer tag on the element under the bridge. >> Remembering of course that the ground is layer=0, so unless something >> under a bridge is in a tunnel it too is layer=0. > > The ground is "usually" layer=0. It doesn't really have to be. Imagine > more then 5 bridges stacked above ground: the ground couldn't be Layer > 0 because Layer's range is from -5 to 5. Imagine more than 10 bridges stacked. The ground couldn't be any layer. The -5/5 limits are a limitation of our tagging, and can be fixed in at least two ways (going beyond or using non-integers). _______________________________________________ Tagging mailing list [email protected] http://lists.openstreetmap.org/listinfo/tagging
