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 _______________________________________________ talk mailing list talk@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk
