I have an underground parking lot (completly under surface) with footway at surface (above it). In OSM the parking lot is mapped like this:
building=yes + building:levels=0 + building:levels:underground=1 + some parking tags. footway on surface is only highway=footway
The problem is when I run JOSM validation it gives me error that building and highway are crossing. How do I properly fix this? Should I put layer=-1 to the underground parking?
Yes, whenever you stack objects that are not crossing you have to put layer=* on them so that it is clear in what order they appear from bottom to top. If no layer tag is attached that defaults to layer=0. It’s customary to put layer=0 on an object on ground level but you can chose arbitrary values as long as the order is clear.
How does this question relate to Android? You would have better placed it in the Questions and Answers section.
@stevenshaw Please reply soon on https://forum.openstreetmap.org/viewtopic.php?pid=745863#p745863 to prevent locking your account.