Data Discovery (ACDD)

The netCDF Group at Unidata recommended a set of netCDF attributes (the NetCDF Attribute Convention for Dataset Discovery) to enable data discovery nearly a decade ago. This convention was designed to augment the Climate-Forecast conventions that were already being used to ease access to data in netCDF by tools. The ACDD was adopted as the basis for the ncISO tool developed at NGDC and incorporated into THREDDS with the goal of providing ISO 19115-compliant discovery metadata for datasets in THREDDS that supported the ACDD. The governance of these conventions has since been taken over by the ESIP Documentation Cluster.

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This page includes ACDD recommendations at three levels: highly recommended, recommended, and suggested.

==Attribute Convention for Data Discovery - Highly Recommended==

These attributes are highly recommended by the Attribute Convention for Data Discovery

Source: ACDD Home Page

Concept	Description	Dialect (Fit) Paths
Resource Title	A short description of the resource. The title should be descriptive enough so that when a user is presented with a list of titles the general content of the data set can be determined.	ADIwg /adiwg:project/adiwg:idinfo/adiwg:citation/adiwg:citeinfo/adiwg:title DIF /dif:DIF/dif:Entry_Title DIF /dif:DIF/dif:Data_Set_Citation/dif:Dataset_Title DCAT /dct:title Dryad dcterms:title ECHO /*/echo:ShortName>/*/echo:LongName ECS /*/ecs:ShortName > /*/ecs:LongName EML /eml:dataset/eml:title/eml:text FGDC /fgdc:metadata/fgdc:idinfo/fgdc:citation/fgdc:citeinfo/fgdc:title HDF5.1 /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Attribute[@Name='title']/hdf5:Data/hdf5:DataFromFile HDF5.1 /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Group[@Name='METADATA']/hdf5:Group[@Name='COLLECTIONMETADATA']/hdf5:Attribute[@Name='LongName']/hdf5:Data/hdf5:DataFromFile ISO /*/gmd:identificationInfo/*/gmd:citation/gmd:CI_Citation/gmd:title/gco:CharacterString ISO-1 /mdb:MD_Metadata/mdb:identificationInfo/*/mri:citation/cit:CI_Citation/cit:title/gco:CharacterString UMM /umm:UMM/umm:CollectionCitation/umm:Title OGC-SOS /sos:Capabilities/ows:ServiceIdentification/ows:Title SERF /serf:SERF/serf:Entry_Title THREDDS /thredds:catalog/thredds:dataset/@name THREDDS /thredds:catalog/thredds:dataset/thredds:metadata/dc:title THREDDS //thredds:dataset[1]/@name netCDF /nc:netcdf/nc:attribute[@nc:name=title]/@nc:value
Abstract	A paragraph describing the resource. Note: This concept is called "Desciption" in Catalog Services for the Web.	ADIwg /adiwg:project/adiwg:idinfo/adiwg:descript/adiwg:abstract DIF /dif:DIF/dif:Summary/dif:Abstract DCAT /dct:description Dryad dcterms:description ECHO /*/echo:Description ECS /*/ecs:CollectionDescription EML /eml:dataset/eml:abstract/eml:descendant FGDC /fgdc:metadata/fgdc:idinfo/fgdc:descript/fgdc:abstract HDF5.1 /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Attribute[@Name='summary']/hdf5:Data/hdf5:DataFromFile HDF5.1 /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Group[@Name='METADATA']/hdf5:Group[@Name='COLLECTIONMETADATA']/hdf5:Attribute[@Name='CollectionDescription']/hdf5:Data/hdf5:DataFromFile ISO /*/gmd:identificationInfo/*/gmd:abstract/gco:CharacterString ISO-1 /mdb:MD_Metadata/mdb:identificationInfo/*/mri:abstract/gco:CharacterString UMM /umm:UMM/umm:Summary OGC-SOS /sos:Capabilities/ows:ServiceIdentification/ows:Abstract SERF /serf:SERF/serf:Summary/serf:Abstract THREDDS //thredds:dataset/thredds:documentation[@type='abstract'] THREDDS //thredds:metadata/thredds:documentation[@type='abstract'] netCDF /nc:netcdf/nc:attribute[@nc:name='summary']/@nc:value
Theme Keyword	A word or phrase that describes some aspect of a resource. Can be one of several types. Note: The general identification keywords usually have a type of "theme" and are refered to as "theme keywords". Other types and vocabularies are used for other information. Service Entry Resource Format (SERF) requires a Science and a Service GCMD Keyword. This concept is called Subject in the CSW Specification.	ADIwg /adiwg:project/adiwg:idinfo/adiwg:keywords/adiwg:theme/adiwg:themekey DIF (1) /dif:DIF/dif:Parameters/dif:Category DIF (1) /dif:DIF/dif:Parameters/dif:Topic DIF (1) /dif:DIF/dif:Parameters/dif:Term DIF (1) /dif:DIF/dif:Parameters/dif:Variable_Level_1 DIF (1) /dif:DIF/dif:Parameters/dif:Variable_Level_2 DIF (1) /dif:DIF/dif:Parameters/dif:Variable_Level_3 DIF (1) /dif:DIF/dif:Parameters/dif:Detailed_Variable DCAT /dct:keyword Dryad dcterms:subject ECHO (1) /*/echo:ScienceKeywords/echo:ScienceKeyword/echo:CategoryKeyword ECHO (1) /*/echo:ScienceKeywords/echo:ScienceKeyword/echo:TopicKeyword ECHO (1) /*/echo:ScienceKeywords/echo:ScienceKeyword/echo:TermKeyword ECHO (1) /*/echo:ScienceKeywords/echo:ScienceKeyword/echo:VariableLevel1Keyword/echo:Value ECHO (1) /*/echo:ScienceKeywords/echo:ScienceKeyword/echo:VariableLevel2Keyword/echo:Value ECHO (1) /*/echo:ScienceKeywords/echo:ScienceKeyword/echo:VariableLevel3Keyword ECHO (1) /*/echo:ScienceKeywords/echo:ScienceKeyword/echo:DetailedVariableKeyword ECS (1) /*/ecs:DisciplineTopicParameters/ecs:DisciplineKeyword ECS (1) /*/ecs:DisciplineTopicParameters/ecs:TopicKeyword ECS (1) /*/ecs:DisciplineTopicParameters/ecs:TermKeyword ECS (1) /*/ecs:DisciplineTopicParameters/ecs:VariableKeyword EML (1) /eml:dataset/eml:keywordSet/eml:keyword/eml:text FGDC /fgdc:metadata/fgdc:idinfo/fgdc:keywords/fgdc:theme/fgdc:themekey HDF5.1 (1) /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Attribute[@Name='keywords']/hdf5:Data/hdf5:DataFromFile HDF5.1 (1) /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Group[@Name='METADATA']/hdf5:Group[@Name='COLLECTIONMETADATA']/hdf5:Group[@Name='DisciplineTopicParameters']/hdf5:Group/hdf5:Attribute[@Name='ECSDisciplineKeyword']/hdf5:Data/hdf5:DataFromFile HDF5.1 (1) /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Group[@Name='METADATA']/hdf5:Group[@Name='COLLECTIONMETADATA']/hdf5:Group[@Name='DisciplineTopicParameters']/hdf5:Group/hdf5:Attribute[@Name='ECSTermKeyword']/hdf5:Data/hdf5:DataFromFile HDF5.1 (1) /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Group[@Name='METADATA']/hdf5:Group[@Name='COLLECTIONMETADATA']/hdf5:Group[@Name='DisciplineTopicParameters']/hdf5:Group/hdf5:Attribute[@Name='ECSTopicKeyword']/hdf5:Data/hdf5:DataFromFile HDF5.1 (1) /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Group[@Name='METADATA']/hdf5:Group[@Name='COLLECTIONMETADATA']/hdf5:Group[@Name='DisciplineTopicParameters']/hdf5:Group/hdf5:Attribute[@Name='ECSVariableKeyword']/hdf5:Data/hdf5:DataFromFile HDF5.1 (1) /hdf5:HDF5-File/hdf5:RootGroup/hdf5:Group[@Name='METADATA']/hdf5:Group[@Name='COLLECTIONMETADATA']/hdf5:Group[@Name='DisciplineTopicParameters']/hdf5:Group/hdf5:Group[@Name='ECSParameter']/hdf5:Attribute[@Name='ECSParameterKeyword']/hdf5:Data/hdf5:DataFromFile ISO (1) /*/gmd:identificationInfo/*/gmd:descriptiveKeywords/gmd:MD_Keywords[gmd:type/gmd:MD_KeywordTypeCode=[normalize-space()="theme"]]/gmd:keyword/gco:CharacterString ISO-1 /mdb:MD_Metadata/mdb:identificationInfo/*/mri:descriptiveKeywords/mri:MD_Keywords[mri:type/mri:MD_KeywordTypeCode=[normalize-space()="theme"]]/mri:keyword/gco:CharacterString UMM (1) /umm:UMM/umm:ScienceKeywords/umm:Category UMM (1) /umm:UMM/umm:ScienceKeywords/umm:Topic UMM (1) /umm:UMM/umm:ScienceKeywords/umm:Term UMM (1) /umm:UMM/umm:ScienceKeywords/umm:VariableLevel1/umm:Value UMM (1) /umm:UMM/umm:ScienceKeywords/umm:VariableLevel1/umm:VariableLevel2/umm:Value UMM (1) /umm:UMM/umm:ScienceKeywords/umm:VariableLevel1/umm:VariableLevel2/umm:VariableLevel3/umm:Value UMM (1) /umm:UMM/umm:ScienceKeywords/umm:DetailedVariable OGC-SOS (1) /sos:Capabilities/ows:ServiceIdentification/ows:Keywords[ows:Type='theme']/ows:Keyword SERF /serf:SERF/serf:Keyword THREDDS (1) //thredds:metadata/thredds:keyword THREDDS (1) //thredds:dataset/thredds:keyword netCDF (1) /nc:netcdf/nc:attribute[@nc:name=keywords]/@nc:value

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. 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.

Data Discoverability /Accessibility