[Tagging] Layer=* tags disappearing
Nathan Edgars II
neroute2 at gmail.com
Tue Oct 12 17:37:30 BST 2010
On Tue, Oct 12, 2010 at 12:11 PM, M∡rtin Koppenhoefer
<dieterdreist at gmail.com> wrote:
> 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?
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).
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