Thank you for your tight and touching reply.  I have seen it happen where someone will enter layer=2 (for the third layer that might be there because there may be a layer=1 that isn't clearly known).

We've now got this one straightened out, and clearly!

I remember when AA was killed there, indeed such a tragedy was big news.

Yes, layer=0 isn't normally used, it is simply "known" (and implicitly used as level ground).  I know Mapillary or StreetView can be used.  The more inputs, the better, the more certain the knowledge (at least one person, strongly asserting as reality), the better.

This is firmly nailed in place as-is.