Hi, I have thought through this again and think we should keep it simple and stupid (KISS):
Am Wed, 3 Aug 2011 20:36:38 +0200 schrieb Gregor Horvath <gre...@ediwo.com>: > ** splitting of ways (old ID would then point to only half) > A split to A,B: > A.superseded_by = B > A does not get deleted In this case A does not get deleted. It alters it's meaning because the old ID points only to the half. But that is not different to adding or editing a tag of that ID. This can also change the meaning of the ID. I think it is not possible to manage a change history of ID meanings. All we can do is provide a replacement ID when an ID is deleted. This can not be an exact replacement, just a hint. Therefore a rule of thumb is this tag can only be applied to deleted IDs. > ** merging (old ID would become invalid in 50% of cases) > - example 1: Relations for long-distance routes created in several > places until they "meet", and are merged, with one of > them being deleted. > - example 2: a POI node might later be joined to be part of an area > representing a shop; this shop area might later be > joined to others to represent an entire building that > contains several shops > > A,B gets merged to A: > A.superseded_by = B > B deleted (visible=false) > B.superseded_by = A same here: A does not get the tag, because it is not deleted. > > ** supersede multiple objects (a merge operation) > A,B,C gets replaced by C > A.superseded_by = C > B.superseded_by = C > C.superseded_by = A > C.superseded_by = B > A,B deleted (invisible) same here C does not get the tag, because it is not deleted. -- Greg _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
