[Tagging] paved=yes/no

[Richard Mann]

I think surface started as a binary paved/unpaved for roads (with
paved assumed by default, and paved meaning tarmac), and has got
extended to cover cobbled roads, and (subsequently) as a way of adding
more info for tracks/paths.

So for most purposes, the principal distinction is between paved and
not, and that can perfectly well be determined by checking for the
presence of the tag, and whether it's value is "paved".

There's a bit of a grey area for well-maintained unsealed paths/roads,
but the binary paved=yes/no doesn't really help. I tend to use other
clues - that it's got a higher road classification, or is flagged as
being part of a cycle route. It wouldn't hurt if there was a value for
"well-maintained unsealed", perhaps surface=graded?

Richard