[Tagging] Non-orthogonal crossing=* tag proposals: crossing=marked/unmarked vs crossing:markings=yes/no

[Kevin Kenny]

On Fri, May 24, 2019 at 5:02 PM Paul Allen <pla16021 at gmail.com> wrote:
> However, they still pose a problem for the blind.  With macular degeneration you might be
> able to make out stripes but not see the signals.  Which would mean that without OSM
> making a distinction they wouldn't know which type of crossing it was.

Yeah, there really are combinations around here:

does it have signs?
does it have traffic signals?
does it have specific pedestrian-facing traffic signals? (Some
intersections just have you cross at the same time as motor traffic in
your direction rolls)
are the traffic signals pedestrian- or cyclist-controlled? (Is there a
button for you to push?)
does it have pavement markings?

And almost all the combinations are possible. (In addition, there are
other features such as lowered curbs/kerbs that need handling)

I'm fine with leaving crossing=* as it is for legacy compatibility,
but we *do* want to move toward orthogonality, since that's what we've
got on the ground.