Hi,
critique welcome:
Proposal superseded_by tag
--------------------------
OSM ID's do not describe physical objects but geometrical objects on a
map. If an a geometrical object supersedes another one with a different
ID it should be possible to tag this relationship for some better
stabilisation and traceability of ID's.
* new TAG superseded_by=type:ID
example:
superseded_by=way:7867678
superseded_by=node:67668
superseded_by=rel:7897789
I do not think that a superseded tag on the new object is necessary
because it is redundant data and an unnecessary maintenance burden.
* Use Cases ID deletion
Below are the cases for deleting a ID mentioned on the mailing list.
I've added the proposed solution.
** expansion of POI nodes into buildings
node is deleted and gets superseded_by tag pointing to the building
** 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
** superseded by several objects (a split operation).
A gets replaced by B,C
A.superseded_by = B
A.superseded_by = C
** 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
** 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)
** re-mapping of stuff in the course of the license change
- re-structuring of relations
- 0.7 area data type (lots of existing areas get a new ID)
superseded_by tag
** mapping error (mistake)
delete ID, no superseded_by
** restaurant moves, should it keep the same ID? If it is renamed? If
it goes bankrupt, is sold, renovated, and reopened by a different
owner
the node describes a point on the map, not a restaurant,
therefore no new ID in this cases.
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