[Talk-GB] NSL in built-up areas: what source:maxspeed to use?

[Andrew Chadwick]

What value should we use for source:maxspeed=* in built-up areas when
there's no signage or road markings, just street lights? Specifically
the concept expressed in

  http://en.wikipedia.org/wiki/Built-up_area_%28Highway_Code%29

Searching taginfo suggests:

* "source:maxspeed=GB:built-up_area" (+ var: "built_up-area"...)
  From 1385 uses without GB: or UK: prefix for the somewhat uncommon
  maxspeed:default=*, but we could use it for the more usual key too.
  Source: http://taginfo.openstreetmap.org/search?q=maxspeed%3Dbuilt

* "source:maxspeed=GB:restricted_road"
  From 394 uses of similar-looking things in taginfo, most of which are
  UK: prefixed.
  Src: http://taginfo.openstreetmap.org/search?q=maxspeed%3Drestricted

Any other possibilities? I think I prefer the former even if using both
a hyphen and an underscore make it ugly and error-prone. It's the more
common term in everyday parlance, and we're not doing designations here.

There don't seem to be any relevant matches for "lit" or "light".

I'm planning on making a presets bundle for them, so values would need
would need to fit alongside GB:motorway, GB:nsl_dual, GB:nsl_single.

-- 
Andrew Chadwick