class - MD_Identifier

In order for machines and people to distinguish singlton elements cited a Metadata record MD_Metadata , a method to provide a unique identifier.

• Governance - ISO
• Metadata type - administrative
• ICSM Level of Agreement - ⭑⭑

Definition

Provides a value uniquely identifying an object within a namespace

ISO Associations

• MD_Metadata.metadataIdentifier
• MD_ReferenceSystem.referenceSystemIdentifier
• MD_Medium.identifier
• MD_RangeDimension.name
• MD_ImageDescription.imageQualityCode
• MD_CoverageDescription.processingLevelCode
• EX_GeographicDescription.geographicIdentifier
• CI_Citation.identifier
• CI_Party.PartyIdentifier

Sub Elements for class MD_Identifier

• code - (type - charStr) [1..1] alphanumeric value identifying an instance in the namespace, mandatory when identifier is provided
• codespace - (type - charStr) [0..1] identifier or namespace in which the code is valid. Usually a URL path which, when combined with the id, creates a resolvable (dereferencable) URI.
• authority - (class CI_Citation) [0..1] the provider of the id
• version - (type - charStr) [0..1] version identifier for the namespace
• description - (type - charStr) [0..1] natural language description of the meaning of the code value

Discussion

authorities as agents

Some metadata implementations use system information in the authority field however authority implies agency and the CI_Citation object makes it clear an agent (person or, more likely an organisation) should be recorded here, not a system.

indicating authorities

Resolvable identifiers (URIs) for authority likely of interest to MDWG members have been established using persistent identifiers by the Australian Government Linked Data Working Group for use in this field:

• http://linked.data.gov.au/org/ausgin - Australian Geoscience Information Network. Authorises use of pid.geoscience.gov.au-based URIs
• http://linked.data.gov.au/org/agldwg - Australian Government Linked Data Working Group. Authorises use of linked.data.gov.au, the Australian government’s departmentally-independent URI domain allocated for persistent data identifiers
• http://linked.data.gov.au/org/doi - Digital Object Identifier System. The international not-for-profit membership organization providing Digital Object Identifier (DOI)s used for documents and data
• http://linked.data.gov.au/org/handle - the general-purpose digital object identifier system used by amny other systems
• http://linked.data.gov.au/org/igsn - International Geo Sample Number. The non-profit consortium managing unique identifiers for samples and specimens collected from our natural environment
• http://linked.data.gov.au/org/psma - PSMA Australia. Issues identifiers for street addresses in Australia
• http://linked.data.gov.au/org/ror - Research Organization Registry Community. A community-led project to develop an open, sustainable, usable, and unique identifier for every research organization in the world

These identifiers may be used in appropriate authority fields (i.e. with a CI_Citation XML block) to better indicate authority agencies than either a (likely short-lived) website address or just the name of them in text and street address/phone contact information and so on.

More identifiers for more authorities can be added uplon request to the AGLDWG.

Best Practice Recommendations

Therefore - it is recommended that the MDWG develop general advise on the use of MD_Identifier - particularly concerning the use of <mcc:codespace> and leverage the ability of combining this element with its mandatory sibling element <mcc:code> to provide a linkage to a cited resource. It would also be beneficial to discuss other sibling elements <mcc:authority>, <mcc:version> and <mcc:description> and develop any needed advice on their general use.

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UML diagrams

Recommended elements highlighted in yellow

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