Christiaan Welvaart wrote: >> In front of a station, there is a road that must not be used by motor >> vehicles except busses. This road also is an oneway road, with no >> exceptions. Therefore, I consider it natural to tag this >> - oneway = yes >> - (access:)motor_vehicle = no >> - (access:)bus = yes >> This can easily be understood if oneway isn't influenced by the other >> tags. > >> If, however, we consider oneway=yes just another way of saying >> (access:)vehicle:backward=no, then we suddenly have a problem: Neither >> of the two conditional expressions "vehicle:backward" and "bus" is more >> specific than the other one, so we cannot determine whether the yes from >> "bus" or the no from "vehicle:backward" is relevant here. > > This can be defined. As I described it one would have to write > bus:forward=yes , but people may indeed expect bus=yes to work.
Yes, it can be defined, of course. I believe that the results of an "independent evaluation per base key" rule comes close to what many people assume about the tag's meaning (its impossible to match all current expectations, unfortunately, because different people have different, sometimes contradicting opinions in absence of clear definitions) and are rather easy to understand. > It is not clear from the text on the proposal page that > oneway:<transportation mode> is more specific than > <transportation mode>:forward ... It would be nice to have an explicit > description of how all the different tags can be evaluated. I'm going to put together a comprehensive description of how I think access evaluation w.r.t. conditional tagging could work as soon as I have the time. I hope that this will make things clearer. Tobias Knerr _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
