A point or period of time associated with an event in the lifecycle of this thing.
states:
« Recommended practice is to express the date, date/time, or period of time according to ISO 8601-1 [[ISO 8601-1](https://www.iso.org/iso-8601-date-and-time-format.html)] or a published profile of the ISO standard, such as the W3C Note on Date and Time Formats [[W3CDTF](https://www.w3.org/TR/NOTE-datetime)] or the Extended Date/Time Format Specification [[EDTF](http://www.loc.gov/standards/datetime/)].
If the full date is unknown, month and year (YYYY-MM) or just year (YYYY) may be used.
Date ranges may be specified using ISO 8601 period of time specification in which start and end dates are separated by a '/' (slash) character.
Either the start or end date may be missing. »