Verifiability is another topic altogether. My point was in relation to the tags themselves. My point is that information that is subjective, and targets a subset of users, must be built into the tag and not the values. The tag must clearly identify the population that it is relevant to. Whether that be "4WD drivers" or "Daring 4WD drivers". But subjective information in the tag values that is relevant to a subset of the population is a bad idea because the values are not necessarily mutually exclusive, as in your example. So rather than a tag such as "Suitability = Conventional Car; SUV; 4WD" the tags should be along the lines of "Conventional_car_suitability=Y/N"; "SUV_suitability=Y/N"; "4WD_suitability=Y/N" Both subjective and objective tags could be verifiable or unverifiable as verifiability is a functon of the tag values rather than the tag. For a subjective tag, verifiability is more difficult and would normally be statistical e.g. "Recommended" or "Yes" could be defined as, say, "> 95% of the target population successfully pass through". Assuming of course such information is avaialble. For objective tags, verifiability can sometimes be easy like "Width" and others more statistical e.g. a "River" could be defined in terms of its long term annual flow rate -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Thursday, 16 May 2013 8:01 AM To: [email protected] Cc: David Bannon; OSM Australian Talk List Subject: Re: [talk-au] OpenStreetMap in Government
On Tue, May 14, 2013 at 10:51 PM, Ken Self <[email protected]> wrote: Just jumping in here with some ideas. If you have an objective tag it is a function of the track. But if you have a subjective tag then it is a function of the user of the road/track. A tag that is true for some and not true for others is not a good tag. e.g. 4WD_Suitability=Recommended may be true for some daring driver but not for some other cautious driver. What I'm saying has been said many times before -- please see http://wiki.openstreetmap.org/wiki/Verifiability. This guideline is well-established and makes perfect sense to me.
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