[OSM-talk] Key:layer update

[Dave F.]

Are you aware there's a separate wiki page for 'Layer'? No wonder users 
get confused!

I suggest these pages are combined into a page called 'Layer' as most 
users wouldn't search for 'Key:*'

On 09/03/2014 10:30, Richard Z. wrote:
> Hi,
>
> for some time now I have been working on the wiki page to state the rules
> as clearly as possible.. hope that most of the improvements are fairly
> uncontroversial. Some of the changes:
>
> * the vertical ordering established by the layer values is valid exactly only
>    in the point where the ways cross or objects overlap
>
> * define layer as higher value means above, lower value means bellow. Avoid
>    the complicated layer=0 definition as "the natural ground level as it
>    would be shown by contour lines on a topographic map". Explicit layer=0
>    seems to be deprecated now.
>
> * layer on ways should be used only in combination with one of tunnel=*, bridge=*,
>    highway=steps, highway=elevator, covered=* or indoor=yes. For areas, it could
>    be used in combination with tags such as man_made=bridge, building=* and similar.
>    The motivation for this is to make it easy for validators to spot errors such
>    as when the wrong segment is accidentaly tagged, bridge/tunnel forgotten, or
>    someone tags excessively long ways for no good reason - common problem with
>    waterways and elevated roads/railroads.
>    I have validated this rule for ways in large parts of the world, there are
>    exceptions which currently I do not know hot to tag better but those are rare.
>
> * in some cases "level" may be more appropriate than "layer"
>
> https://wiki.openstreetmap.org/w/index.php?title=Key%3Alayer&diff=999107&oldid=935491
>
>
> Richard
>
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>


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