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| − | This is an '''unofficial proposal for a "permanent ID" for OpenStreetMap ([[OSM]])'''.
| + | #REDIRECT [[Permanent_ID_for_OSM]] |
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| − | See https://wiki.openstreetmap.org/wiki/Permanent_ID for a more official state of discussions.
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| − | The goal is to get an opaque fixed length ASCII string. And that are the design considerations:
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| − | * The OSM id alone is not stable enough (as probably most agree); and it can represent many concepts (and that's by design in OSM).
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| − | * The version no. of the object is needed which makes clear which tags are (or have been) referred to.
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| − | * Coordinates are needed, because a change of the geometry does not increment the version number.
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| − | So a stable Permanent ID could have the following form (which leads to a fixed length string of 35 chars in total):
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| − | [N|W|R]<osm_id>#<version>[+|-]<lon>[+|-]<lat>
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| − | where:
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| − | * N,W,R stands for Node, Way, or Relation.
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| − | * osm_id is left-padded with zeros to get 10 chars ("digits").
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| − | * version is 4 digits left padded with zeros.
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| − | * coordinates have 5 fixed decimal places (lat is 2 and lon is 3 digits wide, both are signed and left-padded with zeros).
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| − | Example: "Schloss Kyburg" (Castle Kyburg) has relation 1169711,
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| − | version #5 at coordinates 47.4584, 8.74343 which becomes following
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| − | Permanent ID:
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| − | R0001169711#0005+47.45840+008.74343
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| − | Service: A service which return most recent Permanent ID given an object has been changed (thus having another Permanent ID).
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