On 2013-03-17 14:02, sk53.osm wrote:
> Yes, I believe in some cases they are signposted: in which case a ref=* is entirely appropriate. > > W.r.t other commenters, I do not believe that it is the role of OSM to hold internal identifiers, however authoritative, for any object as a matter of course. Certainly they should not be placed in tags whose usage is widely used for both renderers and many other applications (For instance, I don't want navit to tell me turn left into U1699 MacNaughton Crescent [1]). Otherwise we'll start putting NLPG ref=* on every address, or if copyright permits, OSGB TOIDs on every object. Surely we aim to create our own map, not some copy of what the council holds. Our map is a synthesis of many, many sources - that's part of the power of OSM. Facts are facts, so it shouldn't be a surprise that they are the same on different maps. Either the road IS the A123, or it isn't. How that gets rendered/used depends which source domain you choose to reflect in the ref tag. The power to number roads (in the sense we are talking about here) is vested in some body; if they say it is the A123 then that's the end of the story from that point of view. The wiki page for ref=* suggests using official_ref=* for the authoritative information when this differs from the evidence on the ground. > A secondary consideration is that we know that many of these 'authoritative' sources contain errors, both of commission and omission (I've blogged about several types of these). Like OSM and OSGB data, I am sure local council data are also prone to time-based degradation. A significant service which OSM can provide is a second independent look at the geography of Britain. Surely the point of having an authoritative source, is that is cannot contain errors - it IS the truth, by definition. It can contain unintended values, but that's different. If the highways authority has resolved to reclassify a road, but has omitted so far to reflect that in the database, then a truly authoritative database would still be correct; it can only be an "error" if you say that the highways committee minutes are authoritative and the database is merely a derivation. My argument here is one of definition and semantics, but I think that's quite important when the information providers and consumers need to understand each other unambiguously. Can you give links to your blogs? I'm also interested in the criteria that Highland use to classify roads as tertiary or minor. The Links: ------ [1] http://www.openstreetmap.org/browse/way/187103578 [2] http://derickrethans.nl [3] http://xdebug.org [4] http://xdebug.org/donate.php [5] http://lists.openstreetmap.org/listinfo/talk-gb
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