On Thu, Jun 7, 2018 at 11:11 PM, Andy Townsend <ajt1...@gmail.com> wrote:
> On 07/06/18 23:00, Peter Elderson wrote: > >> I think landuse=forest should remain intact, for cases where forestry is >> actually how the land is used. >> So the tag is not deprecated, it's just applicated more consistently. >> > > So you're proposing to change the meaning of a tag that has 3.5 million > uses? > > I'm sure that you have only the best of intentions, but, er, good luck > with that :) > Indeed. Others have pointed out elsewhere that the only way to make this sort of thing work is with new tags, such as happened with landuse=farm. Landuse=farm was ambiguous in meaning, and the meaning was unclear in the wiki. It has been superseded with landuse=farmyard and landuse=farmland, which cover the two cases which were formerly dealt with by landuse=farm. It is also clear (to me) that we should strive to create keys which have unambiguous meanings in British English (since that is the dialect used by OSM). Landuse=forest could mean a group of trees which are not consistently used by a single organization for anything (and often called "Xyz Forest" or "Pqr Wood"), or it could mean an area used for forestry (and might currently have stumps, saplings or mature trees). Therefore we should be promoting landuse=forestry (unambiguous) and landcover=trees (somewhat ambiguous, but for use where forestry isn't applicable), or whatever we eventually (3o years from now?) decide upon. To a large extent, the problem we currently have with landuse=forest is that it should have originally been named landuse=forestry to prevent the ambiguous usage we now have with landuse=forest. It's no good arguing that the wiki should explain ambiguous tags because people with English as a first language often do not look at the wiki (they assume the tag means what it says). It would help, though, if editor presets offered extra guidance (at least at the first use) such as pointing out that landuse=forestry and landcover=trees are possible alternatives and which should be used in which circumstance (again, assuming those are the two we decide upon 97 years from now). It's no good saying that a mass edit can fix it. A mass edit (along with changes to editor presets and renderers) could only work if the tag were unambiguous and used correctly in 99.99% of cases. Unless the proposer is willing to personally survey each use and decide whether or not the new tag is applicable, mass edits of ambiguous tags won't work. A mass edit might be sensible with a tag that is mis-spelled, but it is not sensible for a tag which has been used to map two or more different types of object that we now realize should be mapped differently. I now give you a quote from Fred Brooks Jr: The management question, therefore, is not *whether* to build a pilot system and throw it away. You *will* do that. […] Hence *plan to throw one away; you will, anyhow.* He was writing of software projects. And he's since partially recanted by saying it's applicable only to waterfall development. But the concept still applies here. The first time you tackle a software project (or design a mapping system like OSM) you don't fully comprehend the requirements or how it will actually be used. What you end up with is imperfect, but you also learn how to do it better the next time. OSM evolved in an ad-hoc way. The result is a set of tags which aren't orthogonal and which aren't all intuitive. The ONLY way you can fix it is with a new project that starts from scratch and requires everything to be mapped from scratch (otherwise all you've done is fixed "spelling errors" in tag names). And, if you do that, even if what you come up with is perfect it will not remain so because people keep finding new types of things to match. There isn't going to be a "next time" with OSM (feel free to prove me wrong by forking it and encouraging people to enter all the data from scratch). The best we can do with things like landuse=forest is come up with two or more new tags, promote the new tags, maybe have editors warn that the old tag is deprecated, and let the old tag fade away. -- Paul
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