A date associated with an event in the life cycle of the resource.Typically, Date will be associated with the creation or availability of the resource. Recommended best practice for encoding the date value is defined in a profile of ISO 8601 [W3CDTF] and follows the YYYY-MM-DD format.
The date should be formatted according to the W3C encoding rules for dates and times : Complete date: - YYYY-MM-DD (e.g. 1997-07-16)where: - YYYY [four-digit year] is mandatory- MM [two-digit month (01=January, etc.)] is optional- DD [two-digit day of month (01 through 31)] is optional
Do not confuse with
ISO 8601 [W3CDTF] http://www.w3.org/QA/Tips/iso-date