Key:previously
 previously
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| Description |
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Links a feature to a different, older feature that represented the same real-world object. 
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| Group: lifecycle |
| Used on these elements |
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| Status: in use |
| Tools for this tag |
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The key previously=* is used to link a feature to a different (sometimes deleted) feature that formerly represented the same real-world object. It can be used to reconstruct the complete history of a feature that may have at different points been converted between different element types (for example from a node to a way, or a way to a relation).
Example values
Values for this key generally take the form of either node:, way:, or relation: followed by a numeric element ID, for example previously=node:3607236412.
A minority of values (about 12%) use a space rather than : to separate the element type from its ID; e.g. previously=way 749294118.
Occasionally (about 1% of the time) the value will contain multiple element IDs, separated by semicolons, like previously=node:7217482200;way:773891389.
Other usage
A tiny fraction of existing usage (less than 1%) appears to use previously=* to describe what the feature used to be, rather than to identify an old element that once represented that feature. In nearly all of these cases, the value appears to be a previous value for name=* and would perhaps better be tagged as was:name=*.