Key:check_date
 check_date
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| Description |
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Date of latest review of the data. Format: YYYY-MM-DD. 
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| Group: annotations |
| Used on these elements |
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| Useful combination |
| See also |
| Status: de facto |
| Tools for this tag |
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The tag check_date=* is used:
- to document the date when the existence of an object was last checked and
- as a prefix (check_date:*=*), e.g. in check_date:opening_hours=*, to document when a specific tag was last checked. This is particularily useful for tags with information that change often, such as opening_hours=* or collection_times=*.
The date should be specified using the 
ISO 8601 format YYYY-MM-DD.
Examples
A road that was still under construction on 2 June 2021:
highway=construction check_date=2021-06-02
A road under construction whose planned opening date (5 October 2021) has been checked on 2 June 2021:
highway=construction opening_date=2021-10-05 check_date:opening_date=2021-06-02
A postbox that still existed on 21 September 2021 but whose collection times have probably not been checked since 13 May 2021:
amenity=post_box collection_times=Mo-Fr 09:00 check_date=2021-09-21 check_date:collection_times=2021-05-13
Notes
- The original idea was to use check_date=* to document the date when an object as a whole (i.e. all its tags) have last been checked. However, it was also used to indicate only a partial survey. It has then been used by StreetComplete (and possibly by others) to document the date when only its existence was last checked due to it often being impractical to check all tags of an object.[1]
- check_date is also used as a suffix (e.g. in collection_times:check_date=* or opening_hours:check_date=*), but much less than as a prefix.[2][3]
Synonymous tags in use
There are a number of other tags in use for documenting the date of a survey or update. Apparently there is no clear consensus as yet on which tag to use. You should try to use check_date=* or other of those tags that others have already used for the same purpose to avoid creating new duplicates. Do note, however, that not all of the tags listed here mean exactly the same thing.
Deprecated tags
See also
- survey:date=* - Date of last time the feature was surveyed
- Overpass API query for mailboxes colored by the validity of the collection_time tag - example for QA of amenity=post_box
- Sophox query for features checked after they were edited – examples of mapper confusion about the purpose of the check_date=* key
References
- ↑ https://lists.openstreetmap.org/pipermail/tagging/2021-August/062147.html
- ↑ https://taginfo.openstreetmap.org/keys/opening_hours%3Acheck_date#overview https://taginfo.openstreetmap.org/keys/check_date%3Aopening_hours
- ↑ https://taginfo.openstreetmap.org/keys/collection_times%3Acheck_date#overview https://taginfo.openstreetmap.org/keys/check_date%3Acollection_times