Field Definitions are Available Here
Collection
TBD
Mandatory if applicable
Keyword used to describe the general discipline area of the collection. A collection can conceivably cover several disciplines.
Earth Science
ECSTopicKeyword, ECSTermKeyword, ECSVariableKeyword, ECSParameterKeyword
Earth Science
Must be used with ECSTopicKeyword, ECSTermKeyword, ECSVariableKeyword.
METADATA > COLLECTIONMETADATA > DisciplineTopicParameters > DisciplineTopicParametersContainer.ECSDisciplineKeyword
/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:keyword/gco:CharacterString
Note: if used, see also - /gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:type/gmd:MD_KeywordTypeCode
Descriptive Information