The date the source for this resource was retrieved. The source that was retrieved should be indicated with pav:retrievedFrom. The agent that performed the retrieval may be specified with pav:retrievedBy. This property is normally used in a functional way, although PAV does not formally restrict this. The value is of type xsd:dateTime, for instance "2013-03-26T14:49:00+01:00"^^xsd:dateTime. The timezone information (Z for UTC, +01:00 for UTC+1, etc) SHOULD be included unless unknown. If the time (or parts of time) is unknown, use 00:00:00Z. If the day/month is unknown, use 01-01, for instance, if we only know September 1983, then use "1983-09-01T00:00:00Z"^^xsd:dateTime.