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Temporal reference system

Name Temporal reference system
Definition Description of the temporal reference system(s) used in the data source.
Obligation
  • dataset or dataset series: conditional, mandatory if the spatial data set or one of the features contains temporal information that is not related to the Gregorian Calendar or Coordinated Universal Time
  • service: not applicable
Multiplicity [0..*]
Example Code (URI): http://www.opengis.net/def/trs/USNO/0/GPS
Code (free text): Julian calendar
The temporal reference system of the data source is specified by setting:
 
  • the code as the unique identifier of the coordinate reference system by specifying the unique source code (URI) of the system or by specifying free text, or
  • code, code space, and code space version that in combination uniquely identify the time reference system.

Unique identifiers of temporal reference systems specified by formal, authorized and well-known registers must be used, if they exist for the temporal reference system used in the data set (eg OGC Temporal Reference Systems). Otherwise, the metadata editor enters the value as free text when specifying the metadata.

Technical data
 
INSPIRE equivalent Temporal Reference System
Comparison with INSPIRE equivalent
ISO equivalent [187] referenceSystemIdentifier
Comparison with ISO equivalent
XPath referenceSystemInfo/*/referenceSystemIdentifier
Data type RS_Identifier
Domain RS_Identifier<<DataType>>;
  • code (URI or free text)
  • code space
  • version
Implementation instructions The temporal reference system must be documented if the spatial data set or one of the features contains temporal information that is not related to the Gregorian Calendar or Coordinated Universal Time.

Encoding example 1: Specifying a unique identifier of the temporal reference system
 
<gmd:MD_Metadata...
...
     <gmd:referenceSystemInfo>
         <gmd:MD_ReferenceSystem>
             <gmd:referenceSystemIdentifier>
                 <gmd:RS_Identifier>
                     <gmd:code>
                        <gmx:Anchor xlink:href="http://www.opengis.net/def/trs/USNO/0/GPS">GPS time</gmx:Anchor>
                     </gmd:code>
               </gmd:RS_Identifier>
             </gmd:referenceSystemIdentifier>
         </gmd:MD_ReferenceSystem>
     </gmd:referenceSystemInfo>
...
</gmd:MD_Metadata>

Encoding example 2: Specifying temporal reference system code value as free text
 
<gmd:MD_Metadata...
...
     <gmd:referenceSystemInfo>
         <gmd:MD_ReferenceSystem>
             <gmd:referenceSystemIdentifier>
                 <gmd:RS_Identifier>
                     <gmd:code>
                         <gco:CharacterString>Julian calendar</gco:CharacterString>
                     </gmd:code>
               </gmd:RS_Identifier>
             </gmd:referenceSystemIdentifier>
         </gmd:MD_ReferenceSystem>
     </gmd:referenceSystemInfo>
...
</gmd:MD_Metadata>