[OSM-newbies] Is there any tag for say "seeing in"?

[SomeoneElse]

  On 24/09/2010 11:03, AlfonZ wrote:
> I think start_date (accompanied by end_date) might be what you are 
> looking for.
> http://wiki.openstreetmap.org/wiki/Key:start_date
> http://wiki.openstreetmap.org/wiki/Key:end_date
>
Unfortunately, as noted on the end_date page, "This is ... a highly 
unsupported and untested tag."

Searching the mailing lists for those tags and e.g. "fourth dimension" 
will find lots of discussions (e.g. "fourth dimension" 
site:lists.openstreetmap.org/pipermail).

Going back to the other question though, and when users "saw" stuff is 
mostly there in node and way history.  For example, 
http://www.openstreetmap.org/browse/way/43968101/history shows that 
someone saw that a road was there in November 2009 and somebody else saw 
that it had a speed limit in September 2010.  Obviously this assumes 
that people add features to the map as soon as they see them, but it's 
better than nothing.

Cheers,
Andy