| period | supplies a pointer to some location defining a named
      period of time within which the datable item is understood to
      have occurred. | 
| when | supplies the value of the date or time in a standard form,
      e.g. yyyy-mm-dd.| Zustand  | Optional |  | Datentyp  |  |  | Werte  | A normalized form of temporal expression conforming to the W3C
	XML Schema Part 2: Datatypes Second Edition. |  Examples of W3C date, time, and date & time formats. <date when="1945-10-24">24 Oct 45</date> <date when="1996-09-24T07:25:00Z">September 24th, 1996 at 3:25 in the morning</date> <time when="1999-01-04T20:42:00-05:00">Jan 4 1999 at 8 pm</time> <time when="14:12:38">fourteen twelve and 38 seconds</time> <date when="1962-10">October of 1962</date> <date when="--06-12">June 12th</date> <date when="---01">the first of the month</date> <date when="--08">August</date> <date when="2006">MMVI</date> <date when="0056">56 AD</date> <date when="-0056">56 BC</date>  |  This list begins in  the year 1632, more precisely on Trinity Sunday, i.e. the Sunday after  Pentecost, in that year the <date calendar="Julian" when="1632-06-06">27th of May (old style)</date>.  |  <opener>  <dateline>   <placeName>Dorchester, Village,</placeName>   <date when="1828-03-02">March 2d. 1828.</date>  </dateline>  <salute>To    Mrs. Cornell,</salute> Sunday <time when="12:00:00">noon.</time> </opener>  |  
  | 
| notBefore | specifies the earliest possible date for the event in
	  standard form, e.g. yyyy-mm-dd.| Zustand  | Optional |  | Datentyp  |  |  | Werte  | A normalized form of temporal expression conforming to
	the W3C XML Schema Part 2: Datatypes Second
	Edition. |  
  | 
| notAfter | specifies the latest possible date for the event in
	  standard form, e.g. yyyy-mm-dd.| Zustand  | Optional |  | Datentyp  |  |  | Werte  | A normalized form of temporal expression conforming to the W3C
	  XML Schema Part 2: Datatypes Second Edition. |  
  | 
| from | indicates the starting point of the period in standard form, e.g. yyyy-mm-dd.| Zustand  | Optional |  | Datentyp  |  |  | Werte  | A normalized form of temporal expression conforming to
	  the W3C XML Schema Part 2: Datatypes Second
	  Edition. |  
  | 
| to | indicates the ending point of the period in standard
	  form, e.g. yyyy-mm-dd.| Zustand  | Optional |  | Datentyp  |  |  | Werte  | A normalized form of temporal expression conforming to
	  the W3C XML Schema Part 2: Datatypes Second
	  Edition. |  
  |