An Atom ⟨category⟩ element classifying a syndication entry. The scheme URI identifies the controlled vocabulary; term is the machine code; label is the human-readable form.

The binding of term depends on scheme:

This conditional rule is enforced by the category-term-scheme-binding invariant. Slicing would be a more natural FHIR-level expression, but slice declarations are not supported on Logical models.

An Atom ⟨entry⟩ (RFC 4287 §4.1.2) representing a single syndicated artefact set — for example an RF2 release package, a FHIR CodeSystem, a FHIR ValueSet, or a FHIR NPM package.

An entry combines the Atom 1.0 entry model with three extension namespaces: NCTS ASF (terminology metadata), SNOMED CT (package dependencies, MD5 hashes), and Ontoserver (permissions, validation state).

Cross-field semantics

When an entry's artefact is a FHIR canonical resource (CodeSystem, ValueSet, ConceptMap, NamingSystem, StructureDefinition, …):

• contentItemIdentifier SHOULD equal the resource's ⟨url⟩.
• contentItemVersion SHOULD equal {url}|{version} (the canonical URL, a pipe, and the version).
• published SHOULD equal the resource's date.
• title SHOULD equal the resource's title where present, else name.
• rights SHOULD reflect the resource's copyright.

When the artefact is a SNOMED CT module:

• contentItemIdentifier SHOULD be the unversioned SNOMED CT module URI (http://snomed.info/sct/{moduleId}).
• contentItemVersion SHOULD be the versioned SNOMED CT URI (http://snomed.info/sct/{moduleId}/version/{YYYYMMDD}).

An Atom 1.0 feed (RFC 4287) used to syndicate terminology releases.

The default XML namespace is http://www.w3.org/2005/Atom. Feeds that use the NCTS ASF profile additionally declare the ncts: namespace and SHOULD include the ncts:atomSyndicationFormatProfile element identifying the profile version.

A feed is an ordered collection of entries (RFC 4287 §4.1). Order is publisher-defined; consumers MUST NOT rely on order to determine recency — use the entry-level updated element instead.

A reduced description of a feed, used inside an entry's ⟨source⟩ element (Atom RFC 4287 §4.2.11).

When an entry is copied, mirrored, or aggregated from one feed into another, the receiving feed SHOULD preserve the originating feed's identity by including a ⟨source⟩ element on the entry. The ⟨source⟩ element carries enough metadata to recover the originating feed even if the entry is later detached from any feed document.

A consumer that re-encounters the same entry ⟨id⟩ in two different feeds can use ⟨source⟩ to disambiguate origin.

An Atom ⟨link⟩ element (RFC 4287 §4.2.7) inside a syndication entry. The core Atom attributes carry the artefact URL and media type; the extension namespaces add file-level integrity and validation metadata.

Integrity

A consumer MUST be able to verify a downloaded artefact's integrity. At least one of md5Hash or sha256Hash SHOULD be present on every link whose rel is alternate or related. Where both are present, sha256Hash is authoritative.

The hash is computed over the byte stream that href resolves to, exactly as published — without any decompression or content-encoding negotiation.

Length

length is the byte count of that same stream. When present, it MUST match what the href resolves to.

Permitted values for the ncts:bundleInterpretation element on an entry whose artefact is a FHIR Bundle. Hints at the publisher's view of the Bundle's contents. The consumer is not obliged to follow the hint.

The single category term used when an entry's scheme is one of the Ontoserver RF2 binary-index URIs (http://ontoserver.csiro.au/syndication/rf2/1.0.0 or …/2.0.0).

All codes from the NCTS ASF category scheme. Used to classify the artefact carried by a syndication entry.

The single category term used by syndication entries that publish a pre-built Ontoserver RF2 binary index — i.e. a zip file containing the on-disk index Ontoserver builds from a SNOMED CT RF2 release, ready to be consumed directly without re-indexing.

Consumers that recognise this artefact type can load the index directly; consumers that do not MUST ignore the entry (the artefact is not a SNOMED CT RF2 release).

Wire-level scheme URI

On the wire, the Atom ⟨category⟩ element's scheme attribute carries one of these URIs — not the canonical of this CodeSystem:

• http://ontoserver.csiro.au/syndication/rf2/1.0.0
• http://ontoserver.csiro.au/syndication/rf2/2.0.0

The trailing path segment is the binary index format version — not the version of the SNOMED CT release contained in the index. A consumer MUST match the scheme URI exactly: an index published as …/rf2/1.0.0 is not interchangeable with one published as …/rf2/2.0.0.

The label paired with this term on the ⟨category⟩ element is conventionally Binary Index.

The set of terms used on a category element's term attribute to identify what kind of terminology artefact a syndication entry carries.

This code system represents the NCTS Atom Syndication Format category scheme, identified by the URI http://ns.electronichealth.net.au/ncts/syndication/asf/scheme/1.0.0.

Every entry SHOULD include at least one category whose scheme is this URI; consumers use this category to decide how to load the linked artefact.