On 2014-06-09 19:25, SomeoneElse wrote : > Martin Koppenhoefer wrote: >> >> >> 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: >> http://taginfo.openstreetmap.org/keys/maxspeed%3Atype#map >> http://taginfo.openstreetmap.org/keys/source:maxspeed#map > > ... 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). > > 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. > > 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). A mixed bag in short. And when one looks at the actual contents of source=*, that's what it is indeed. Sources of all kinds separated with the strictly forbidden semicolon, survey without date, ... So, why not use type and source in the same tag? The strangest is the directive to use type=* if and only if source=* contains source. But, after all, the chap uses the bike when the wife uses the car, doesn't he? Speaking of humor, I liked the icon displayed by taginfo for source:maxspeed: End-of-speed-limit ... be optimistic!!! :-)
Cheers, André.
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