| 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. 
                                 
                                    | 狀態 | 非必備的 |  
                                    | 資料類型 |  |  
                                    | 值 | 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">AD 56</date>
 <date when="-0056">56 BC</date>
 |  
                                    | This list begins inthe 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 | 以標準格式說明該事件可能發生的最早日期,例如年-月-日。 
                                 
                                    | 狀態 | 非必備的 |  
                                    | 資料類型 |  |  
                                    | 值 | A normalized form of temporal expression conforming to
                                       	the W3C XML Schema Part 2: Datatypes Second
                                          	Edition. |  | 
                        
                        
                           | notAfter | 以標準形式標明該事件可能的最晚日期,例如年-月-日。 
                                 
                                    | 狀態 | 非必備的 |  
                                    | 資料類型 |  |  
                                    | 值 | A normalized form of temporal expression conforming to the W3C
                                       	  XML Schema Part 2: Datatypes Second Edition. |  | 
                        
                        
                           | from | 以標準格式表示該段時間的起始點。 
                                 
                                    | 狀態 | 非必備的 |  
                                    | 資料類型 |  |  
                                    | 值 | A normalized form of temporal expression conforming to
                                       	  the W3C XML Schema Part 2: Datatypes Second
                                          	  Edition. |  | 
                        
                        
                           | to | 以標準格式表示該段時間的結束點。 
                                 
                                    | 狀態 | 非必備的 |  
                                    | 資料類型 |  |  
                                    | 值 | A normalized form of temporal expression conforming to
                                       	  the W3C XML Schema Part 2: Datatypes Second
                                          	  Edition. |  |