ADatP-5636 NATO Core Metadata Specification

What it is

ADatP-5636 is the NATO Core Metadata Specification (NCMS): the Allied Data Publication that defines the set of metadata elements NATO expects to travel with an information resource, so that whoever encounters it later can find it, understand its sensitivity, and handle it consistently across the Alliance's information and communication systems. It is one of three companion publications that together make up NATO's metadata infrastructure - ADatP-4774 supplies the confidentiality label syntax, ADatP-4778 supplies the mechanism for actually binding metadata to a data object, and ADatP-5636 supplies the core set of elements those two mechanisms carry. It is a technical data specification, not a management system or a quality clause: it addresses whoever is designing or building a NATO information system, and any Community of Interest (COI) that needs to extend the core set with its own metadata.

The three layers

The specification arranges its elements into three layers. The Security Layer carries the confidentiality labels: originatorConfidentialityLabel and metadataConfidentialityLabel are mandatory, alternativeConfidentialityLabel is optional, and all three are built on STANAG 4774. The Common Layer is "primarily based on the elements defined in ISO 15836:2009 as the Dublin Core Metadata Element Set" and carries the bulk of the specification: groups for Coverage, Date, Description, Format, Identifier, Relation, Rights, Subject and Title, plus standalone elements including contributor, creator, custodian, language, contextActivity, provenance, publisher, source and type. The Information Lifecycle Support Layer carries recordsDisposition, recordsHold, status, updatingFrequency and version, all optional, for the tasks of retention, disposition and status tracking.

Seven elements, everything else optional

Only seven elements are mandatory on every resource (Annex A.1): originatorConfidentialityLabel and metadataConfidentialityLabel from the Security Layer, and creator, dateCreated, identifier, publisher and title from the Common Layer. Of those, creator and publisher carry organisational roles - creator is "An entity primarily responsible for creating the resource", publisher "The entity responsible for making the resource officially available" - and each resource has exactly one of each. Everything else is optional, or conditional on another element being used: geographicEncodingScheme is mandatory only if geographicReference is present and prohibited otherwise, dateCopyrighted only applies if copyright is used, extentQualifier only if extent is used, and reasonForRedaction only if a redaction relation is used.

Composite values follow their own structure. A confidentiality label follows STANAG 4774. A point of contact - used for creator, publisher, custodian, contributor and rightsHolder alike - carries six sub-elements (type, name, affiliation, address, email, phone), of which "only type and name are mandatory"; the other four are prohibited outright when the type is "service" rather than a person or organisation. A time interval follows an optional start, end, name and scheme.

One modelling detail is easy to miss: metadataConfidentialityLabel, the label on the metadata set itself rather than on the resource, has no XML element of its own. It is implemented instead by binding an originatorConfidentialityLabel element to the metadata - an implementer looking for a dedicated tag for it will not find one.

Extending it for a Community of Interest

The NCMS is deliberately a core set, not an exhaustive one, and a Community of Interest with its own metadata needs works through a fixed order of preference: reuse an existing NCMS element; reuse an existing Dublin Core term; define a COI-specific syntax encoding of an existing element only if the existing encoding is not detailed enough; define an entirely new COI-specific element only if nothing existing fits; or reuse an already-established COI-specific XML element unchanged. "All newly developed COI metadata specifications shall follow" the pattern of reusing the NCMS core and adding only what is genuinely COI-specific - the order matters most while a system's data model is still being designed, since retrofitting it after interfaces and stored metadata are fixed is far more expensive.

How it binds

ADatP-5636 carries the technical content; it acquires force through STANAG 5636, the agreement NATO nations ratify, and it reaches a system builder only when a contract, a national authority or an internal NATO programme invokes it for a particular system - not because the document exists. Annex C gives the normative XML schema, in the urn:nato:stanag:5636:A:1:elements namespace, and metadata elements are attached to a data object using the STANAG 4778 binding mechanism: "NCMS metadata elements SHALL be bound to data objects in accordance with STANAG 4778", either embedded directly or referenced from elsewhere.

There is no accredited or government body that assesses conformance with ADatP-5636, and no certificate to hold. What the specification asks of an implementation is that it "contain the mandatory elements to ensure the interoperability of metadata based on the specification"; structural conformance is what the normative XML schema validates, while values drawn from a controlled code list are a separate matter the schema does not check on its own and would need something like Schematron rules to catch.

Standards it references

• STANAG 4778Binds
• ADatP-4774Background
• ADatP-4778Background
• STANAG 4774Background