OpenHistoricalMap/Tags/Key/start_date:edtf
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Description |
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Approximate or uncertain date when the feature came into existence. ![]() |
Group: lifecycle |
Used on these elements |
Requires |
Useful combination |
Status: de facto |
Tools for this tag |
This subkey of start_date=*
qualifies the feature's start date in the Extended Date Time Format, a profile of ISO 8601 that supports times of day, uncertainty, approximation, and seasons.
How to tag
Tag the EDTF start date in start_date:edtf=*
. For backwards compatibility, also set start_date=*
to the most accurate date that can be expressed in that key's more rigid YYYY-MM-DD
format. Do not set start_date=*
to OpenStreetMap's approximations syntax. OHM rejects this syntax in favor of EDTF in start_date:edtf=*
.
Examples
Software support
In iD, you can click the button in the Start Date field to set an EDTF date. iD validates this date and will warn if it is malformed or the
start_date=*
falls outside the range of possible dates described by the EDTF date. If the start_date=*
is expressed in OSM's "approximations" format, iD will flag it as an invalid date and offer to replace it with the equivalent start_date:edtf=*
tag in EDTF format.
No renderer has built-in support for EDTF dates yet.
See also
end_date:edtf=*
- Open Historical Map/Dates And Times
- Open Historical Map/Tags/Proposed/Tag:start date=datespec
Notes and references
- ↑ Optional.
- ↑ Pick the more likely date, or whichever one is less likely to conflict with other features in the same vicinity.
- ↑ Jump up to: 3.0 3.1 3.2 Set notation is more semantically accurate than the older interval notation for this purpose.
- ↑ ISO 8601-1 also allows week numbers, as in
1992-W14/1992-W15
, but EDTF parsers do not reliably support this syntax.
External links
- Extended Date/Time Format (EDTF) Specification
- ANTLR EDTF parser
- Bayou City DAMS Map date input guidelines from the University of Houston