[Tagging] Layer=* tags disappearing

M∡rtin Koppenhoefer dieterdreist at gmail.com
Tue Oct 12 17:11:53 BST 2010

2010/10/12 Nathan Edgars II <neroute2 at gmail.com>:
> On Tue, Oct 12, 2010 at 11:26 AM, Pieren <pieren3 at gmail.com> 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?

>> 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.


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