Documenting Identifiers

From Earth Science Information Partners (ESIP)

Unique identifiers in metadata records are becoming more and more important for data citation and attribution and for identifying resources related to the resource being described in the metadata. Some mechanism must exist for ensuring that these identifiers are unique. This can be accomplished by using an identifier scheme that guarantees uniqueness (UUID) or by specifying the naming authority or namespace for the identifier. It is the responsibility of the manager of the namespace to ensure that the identifiers in that namespace are unique.

Metadata Record Identifiers

As metadata are shared between National and International repositories it is becoming increasing important to be able to unambiguously identify and refer to specific records. This requirement is facilitated by including an identifier for metadata record in the metadata itself.

Resource Identifiers

Metadata must include an unambiguous identifier for the resource that it describes.

Related Resource Identifiers

Metadata records increasingly refer to resources that are related to the resource being described. These external resources can be many different type of things.

ISO Identifiers

ISO 19115 identifiers include two elements: a code and an authority. The code is an alphanumeric value identifying an object in a namespace that is maintained by the authority. The authority is a CI_Citation. There is no agreed upon convention for describing a simple namespace in a CI_Citation. This problem was ameliorated by adding a codespace attribute to the RS_Identifier which could be substituted for MD_Identifier in 19115. This problem was addressed by adding three new CharacterStrings to the MD_Identifier class in ISO 19115-1 (the revision to 19115):

  • codeSpace - which unambiguously defines the namespace for the identifier
  • version - which is a version for the identifier
  • description - a brief description of the meaning of the code

<div="identifiers">==Crosswalks==

ConceptDescriptionDialect (Fit) Paths
Metadata IdentifierA phrase or string which uniquely identifies the metadata file/record.ISO /*/gmd:fileIdentifier/gco:CharacterString
ISO-1 /mdb:MD_Metadata/mdb:metadataIdentifier/mcc:MD_Identifier
DIF /dif:DIF/dif:Entry_Id
Resource IdentifierIdentifier for the resource described by the metadataISO /*/gmd:identificationInfo/*/gmd:citation/gmd:CI_Citation/gmd:identifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO-1 /mdb:MD_Metadata/mdb:identificationInfo/*/mri:citation/cit:CI_Citation/cit:identifier/mcc:MD_Identifier/mcc:code/gco:CharacterString
ECHO /*/echo:DataSetId
ECHO (1) /*/echo:ShortName | /*/echo:LongName
DIF /dif:DIF/dif:Data_Set_Citation/dif:Dataset_DOI
netCDF /nc:netcdf/nc:attribute[@nc:name=id]/@nc:value
THREDDS /thredds:catalog/thredds:dataset/@ID
ADIwg /adiwg:project/adiwg:idinfo/adiwg:ids/adiwg:projguid
Related Resource IdentifierIdentifier for a resource related to the resource being described.ISO (1) /*/gmd:identificationInfo/*/gmd:aggregationInfo/gmd:MD_AggregateInformation/gmd:aggregateDataSetIdentifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO (1) /*/gmd:identificationInfo/*/gmd:extent/gmd:EX_Extent/gmd:geographicElement/gmd:EX_GeographicDescription/gmd:geographicIdentifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO (1) /*/gmd:identificationInfo/*/gmd:processingLevel/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO (1) /*/gmd:dataQualityInfo/gmd:DQ_DataQuality/gmd:report/gmd:DQ_AccuracyOfATimeMeasurement/gmd:measureIdentification/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO (1) /gmi:MI_Metadata/gmi:acquisitionInformation/eos:EOS_AcquisitionInformation/gmi:operation/gmi:MI_Operation/gmi:identifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO (1) /gmi:MI_Metadata/gmi:acquisitionInformation/gmi:MI_AcquisitionInformation/gmi:platform/gmi:MI_Platform/gmi:identifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO (1) /gmi:MI_Metadata/gmi:acquisitionInformation/gmi:MI_AcquisitionInformation/gmi:instrument/gmi:MI_Instrument/gmi:identifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO /gmi:MI_Metadata/gmi:acquisitionInformation/eos:EOS_AcquisitionInformation/eos:sensor/eos:EOS_Sensor/eos:identifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO-1 /mdb:MD_Metadata/mdb:identificationInfo/*/mri:associatedResource/mri:MD_AssociatedResource/mri:name/cit:CI_Citation/cit:identifier/mcc:MD_Identifier/mcc:code/gco:CharacterString
ECHO (1) /*/echo:CollectionAssociations/echo:CollectionAssociation/echo:ShortName
ECHO (1) /*/echo:Spatial/echo:HorizontalSpatialDomain/echo:ZoneIdentifier
ECHO (1) /*/echo:ProcessingLevelId
ECHO (1) /*/echo:Campaigns/echo:Campaign/echo:ShortName | /*/echo:Campaigns/echo:Campaign/echo:LongName
ECHO (1) /*/echo:Platforms/echo:Platform/echo:ShortName | /*/echo:Platforms/echo:Platform/echo:LongName
ECHO (1) /*/echo:Platforms/echo:Platform/echo:Instruments/echo:Instrument/echo:ShortName | /echo:*/echo:Platforms/echo:Platform/echo:Instruments/echo:Instrument/echo:LongName
ECHO (1) /*/echo:Platforms/echo:Platform/echo:Instruments/echo:Instrument/echo:Sensors/echo:Sensor/echo:ShortName | /*/echo:Platforms/echo:Platform/echo:Instruments/echo:Instrument/echo:Sensors/echo:Sensor/echo:LongName
ECHO (1) /*/echo:AssociatedDIFs/echo:DIF/echo:EntryId
Naming AuthorityThe organization responsible for the maintenance of the identifier (namespace)

Note: DIF and ECHO use the Global Change Master Directory (GCMD) keywords.
ISO /*/gmd:identificationInfo/*/gmd:citation/gmd:CI_Citation/gmd:identifier/gmd:MD_Identifier/gmd:authority
ISO-1 /mdb:MD_Metadata/mdb:identificationInfo/*/mri:citation/cit:CI_Citation/cit:identifier/mcc:MD_Identifier/mcc:codeSpace/gco:CharacterString
netCDF /nc:netcdf/nc:attribute[@nc:name=naming_authority]/@nc:value
THREDDS /thredds:catalog/thredds:dataset/@authority
Parent IdentifierA unique identifier for a parent dataset or collectionISO /*/gmd:identificationInfo/*/gmd:aggregationInfo/gmd:MD_AggregateInformation/gmd:aggregateDataSetName/gmd:CI_Citation/gmd:identifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
ISO-1 /mdb:MD_Metadata/mdb:identificationInfo/*/mri:associatedResource/mri:MD_AssociatedResource/mri:name/cit:CI_Citation/cit:identifier/mcc:MD_Identifier/mcc:code/gco:CharacterString
DIF /dif:DIF/dif:Parent_DIF

xPath Note: The xPaths included in this table use several wildcards. // means any path, so //gmd:CI_ResponsibleParty indicates a gmd:CI_ResponsibleParty anywhere in an XML file. /*/ indicates a single level with several possible elements. This usually indicates one of several concrete realizations of an abstract object. For example /*/gmd:identificationInfo could be gmd:MD_Metadata/gmd:identificationInfo or gmi:MI_Metadata/gmd:identificationInfo and gmd:identificationInfo//*/gmd:descriptiveKeywords could be gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords or gmd:identificationInfo/srv:SV_ServiceIdentification/gmd:descriptiveKeywords. Fit: The fit of the dialect path with the concept is estimated on a scale of 1 = excellent two-way fit, 2 = one-way fit or some other problem, 3 - extension required.


Metadata Implementation