MD Identifier

For a value uniquely identifying an object within a namespace.

Elements			Definition and Recommended Practice
1	authority	0..1	Citation to person or party responsible for maintenance of the code value.
2	code	1	The alphanumeric value that uniquely identifies the referenced resource. When the identifer has a permanent URL, then use the `gmx:Anchor` field instead of `gco:CharacterString` field.

1	authority	0..1	Citation to person or party responsible for maintenance of the code value.
2	code	1	The alphanumeric value that uniquely identifies the referenced resource. When the identifer has a permanent URL, then use the `gmx:Anchor` field instead of `gco:CharacterString` field. Example: `urn:ogc:def:crs:EPSG::4326`
3	codeSpace	0..1	Namespace of the system in which the code is valid.
4	version	0..1	The version of the code value. Example: `6.18.3`

M = Mandatory; C = Conditional; R = Recommended; blank cell = user discretion

Community	Element	M	Notes
NOAA Completeness Rubric V2	authority		Same requirements as the ISO standard
	code	M
	codeSpace
	version

OneStop Project	authority		Same requirements as the ISO standard
	code	M
	codeSpave
	version

UML
Links	WGS84: http://www.ngdc.noaa.gov/docucomp/2504d000-8345-11e1-b0c4-0800200c9a66.guide ISO_Identifiers
Examples	For "authority" element: authority: (CI_Citation) title: European Petroleum Survey Group (EPSG) Geodetic Parameter Registry date: (CI_Date) date: 2008-11-12 dateType: (CI_DateTypeCode) citedResponsibleParty: (CI_ResponsibleParty) organisationName: European Petroleum Survey Group contactInfo: (CI_Contact) onlineResource: (CI_OnlineResource) linkage: http://www.epsg-registry.org/ name: European Petroleum Survey Group Geodetic Parameter Dataset description: Registry that accesses the EPSG Geodetic Parameter Dataset, which is a structured dataset of Coordinate Reference Systems and Coordinate Transformations. function: (CI_OnLineFunctionCode) search role: (inapplicable)

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UML
Links	WGS84: https://data.noaa.gov/docucomp/2504d000-8345-11e1-b0c4-0800200c9a66 ISO_Identifiers
Example	For "code" element: `<gmd:code><gmx:Anchor xlink:href="https://dx.doi.org/10.7289/V52Z13FT" xlink:title="DOI"xlink:actuate="onRequest">doi:10.7289/V52Z13FT</gmx:Anchor></gmd:code>`