Key:check_date
 check_date
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| Description |
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Date of latest review of the data  
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| Group: Properties |
| Used on these elements |
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| Useful combination |
| See also |
| Status: in use |
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| Tools for this tag |
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| Wikidata |
| Property:P813 |
The tag is intended to document the last date, when an object as a whole or specific tags of the object were checked and verified. This tag may be used with all items where information is subject to change on a regular basis.
The date should be specified using the 
ISO 8601 basic format YYYY-MM-DD.
Examples:
check_date=* used with highway=construction and opening_date=* documents the last time, when the expected opening date was checked or updated.
To indicate the review of specific tags the key is built from multiple words separated by colons like check_date:collection_times=* or check_date:opening_hours=*. collection_times:check_date=* or opening_hours:check_date=* variants are also used but are far less popular[1][2]
Mapping parties could be run, where critical items with old check dates are surveyed (Example: emergency=defibrillator).
Other 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.
| survey:date=*
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survey_date=*
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survey=*
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| operational_status=*
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operational_status:date=*
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operational_status:note=*
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| last_checked=*
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last_checked:date=*
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last_checked:note=*
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| lastcheck=*
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checked_exists:date=*
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check_date:existence=*
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| updated=*
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stateofrepair=*
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stateofrepair:note=*
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The numbers documented here for tag counts and users are based on data from Taginfo (check_date=2016-07-01).
Issues
The last edit date may have been by an armchair mapper, and does not imply a check date. A local mapper may verify some attributes of an object, but not others. In those cases it's important to know what attribute was checked (e.g. existence, temperature, taste, opening hours, repair status). Variants of this tag, such as check_date:opening_hours=* or checked_exists:date=* may be useful to avoid this problem.
See also
- 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
- source:date=*
- survey:date=*
- Proposed features/changeset_tags
- Proposed features/Second opinion correctness survey (Abandoned)
- Proposed features/Tag:operational_status
- Proposed features/last_checked (Abandoned)
- Proposed features/Checked_by (Abandoned)