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<div class="moz-cite-prefix">On 2014-06-09 19:25, SomeoneElse wrote
:<br>
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<blockquote cite="mid:5395EDF0.7010506@mail.atownsend.org.uk"
type="cite">Martin Koppenhoefer wrote:
<br>
<blockquote type="cite">
<br>
<br>
Actually the "source:maxspeed" tag was discussed years ago (2009
IIRR) on this list and by the time approved. The idea to use
maxspeed:type instead is very new compared to this, and there
wasn't any actual proposal to see whether this was backed by the
community, rather then what appears to be a national initiative
of some folk in the british comunity in order to make up
something different to how it is done elsewhere:
<br>
<a class="moz-txt-link-freetext" href="http://taginfo.openstreetmap.org/keys/maxspeed%3Atype#map">http://taginfo.openstreetmap.org/keys/maxspeed%3Atype#map</a>
<br>
<a class="moz-txt-link-freetext" href="http://taginfo.openstreetmap.org/keys/source:maxspeed#map">http://taginfo.openstreetmap.org/keys/source:maxspeed#map</a>
<br>
</blockquote>
<br>
... another interpretation as to what actually happened is that
"source:blah" was in widespread use since the beginning of time
for "the source of the blah key" (survey, local_knowledge,
whatever). Then at some point people decided to use
"source:maxspeed" to refer to the zone (e.g. if a road's in an
urban area, and urban areas in your country have a 30 km/h speed
limit regardless of signage, then it's OK to say that the "source
of the maxspeed" is something like "DE:zone:30" or similar).
<br>
<br>
In the UK "maxspeed:type" is usually used with "national" speed
limits, not zone-based ones. The source of the maxspeed is
therefore "survey", "local_knowledge" or similar, and
"maxspeed:type" is used to indicate that it is a "national"
maximum speed limit, not a numeric one. It's important to record
what the sign actually says, not just the number that that sign
happens to currently represent - historically the national speed
limit for different classes of road for cars has changed, and it
may again in the future.
<br>
<br>
There was (a couple of years ago) a significant usage of
"maxspeed=national" or similar in the UK. this caused a certain
amount of "toys being thrown out of prams" from people (mostly
from countries where the posted limit is always numeric) who
expected the "maxspeed" value to always be a number. The
compromise was to store store the actual posted sign value in
maxspeed:type, and what number that happens to currently
correspond to in "maxspeed" (and the actual source, if it needs to
be stored, in maxspeed:source for compatibility with other source
keys).
<br>
</blockquote>
A mixed bag in short.<br>
And when one looks at the actual contents of source=*, that's what
it is indeed.<br>
Sources of all kinds separated with the strictly forbidden semicolon,
survey without date, ...<br>
So, why not use type and source in the same tag?<br>
The strangest is the directive to use type=* if and only if source=*
contains source.<br>
But, after all, the chap uses the bike when the wife uses the car,
doesn't he?<br>
Speaking of humor, I liked the icon displayed by taginfo for
source:maxspeed:<br>
End-of-speed-limit ... be optimistic!!! :-)<br>
<br>
Cheers,<br>
<br>
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<td>André.</td>
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