# Metadata Hierarchy

As the release file formats contain a number of concept enumerations, it is necessary to define sets of concepts that represent the allowed values. As well as the enumerated values, other metadata supporting the extensibility mechanism and the concept model is required.

The concept [900000000000441003 | SNOMED CT Model Component (metadata)|](http://snomed.info/id/900000000000441003) is a subtype of the root concept (138875005 <mark style="color:blue;">|</mark>SNOMED CT Concept<mark style="color:blue;">|</mark>), and contains the metadata, supporting the release.

The subtypes of <mark style="color:blue;">|</mark>SNOMED CT Model Component (metadata)<mark style="color:blue;">|</mark> are described in the following table and the top three levels of the hierarchy are shown in the figure below this.

***

**SNOMED CT Model Component (metadata)**

<table data-full-width="true"><thead><tr><th width="214.89453125">Id</th><th width="415.186767578125">Term</th><th width="650.2750244140625">Comment</th></tr></thead><tbody><tr><td>106237007</td><td><mark style="color:blue;">|</mark>Linkage concept (linkage concept)<mark style="color:blue;">|</mark></td><td><p>Concepts that specify</p><ul><li>Semantic Relationships between concepts (246061005 <mark style="color:blue;">|</mark>Attribute<mark style="color:blue;">|</mark>); and</li><li>Asserted associations between statements in a record (416698001 <mark style="color:blue;">|</mark>Link assertion<mark style="color:blue;">|</mark>).</li></ul></td></tr><tr><td>370136006</td><td><mark style="color:blue;">|</mark>Namespace concept (namespace concept)<mark style="color:blue;">|</mark></td><td>Concepts that specify the Extension Namespaces allocated by the SNOMED International.</td></tr><tr><td>900000000000442005</td><td><mark style="color:blue;">|</mark>Core metadata concept (core metadata concept)<mark style="color:blue;">|</mark></td><td>Concepts that are referenced from enumerated fields within the International Release files (the Concept, Description, Relationship, Identifier).</td></tr><tr><td>900000000000454005</td><td><mark style="color:blue;">|</mark>Foundation metadata concept (foundation metadata concept)<mark style="color:blue;">|</mark></td><td>The metadata that supports the extensibility mechanism, and is discussed in more detail in the <a href="https://app.gitbook.com/o/h8Z6qGxuQrzM9vbx5bPT/s/qOI2v58ZsXOoklmwBOk4/">Reference Sets Guide</a>.</td></tr><tr><td>762947003</td><td><mark style="color:blue;">|</mark>OWL metadata concept (OWL metadata concept)<mark style="color:blue;">|</mark></td><td>The OWL metadata concept has subtypes that are used in the OWL<br>reference sets to provide a referencedComponent for some of the definitions or axioms that are required.</td></tr></tbody></table>

***

**SNOMED CT Metadata Hierarchy (2018-01-31) - Core metadata concepts (top 3 levels only)**

[900000000000441003 |SNOMED CT Model Component|](http://snomed.info/id/900000000000441003)\
[900000000000442005 |Core metadata concept|](http://snomed.info/id/900000000000442005)\
[900000000000447004 |Case significance|](http://snomed.info/id/900000000000447004)\
[900000000000448009 |Case insensitive|](http://snomed.info/id/900000000000448009)\
[900000000000017005 |Case sensitive|](http://snomed.info/id/900000000000017005)\
[900000000000020002 |Initial character case insensitive|](http://snomed.info/id/900000000000020002)\
[900000000000449001 |Characteristic type|](http://snomed.info/id/900000000000449001)\
[900000000000227009 |Additional relationship|](http://snomed.info/id/900000000000227009)\
[900000000000006009 |Defining relationship|](http://snomed.info/id/900000000000006009)\
[900000000000225001 |Qualifying relationship|](http://snomed.info/id/900000000000225001)\
[900000000000444006 |Definition status|](http://snomed.info/id/900000000000444006)\
[900000000000073002 |Defined|](http://snomed.info/id/900000000000073002)\
[900000000000074008 |Primitive|](http://snomed.info/id/900000000000074008)\
[900000000000446008 |Description type|](http://snomed.info/id/900000000000446008)\
[900000000000550004 |Definition|](http://snomed.info/id/900000000000550004)\
[900000000000003001 |Fully specified name|](http://snomed.info/id/900000000000003001)\
[900000000000013009 |Synonym|](http://snomed.info/id/900000000000013009)\
[900000000000453004 |Identifier scheme|](http://snomed.info/id/900000000000453004)\
[900000000000294009 |SNOMED CT integer ID|](http://snomed.info/id/900000000000294009)\
[900000000000002006 |SNOMED CT UUID|](http://snomed.info/id/900000000000002006)\
[900000000000450001 |Modifier|](http://snomed.info/id/900000000000450001)\
[900000000000452009 |All|](http://snomed.info/id/900000000000452009)\
[900000000000451002 |Some|](http://snomed.info/id/900000000000451002)\
[900000000000443000 |Module|](http://snomed.info/id/900000000000443000)\
[900000000000445007 |IHTSDO maintained module|](http://snomed.info/id/900000000000445007)\
[466707005 |SNOMED CT Medical Devices module|](http://snomed.info/id/466707005)\
\
[900000000000454005 |Foundation metadata concept|](http://snomed.info/id/900000000000454005) ... (see next table)

***

**SNOMED CT Metadata Hierarchy (2018-01-31) - Foundation metadata concepts (top 3 levels only - some long lists replaced by ...)**

[900000000000441003 |SNOMED CT Model Component|](http://snomed.info/id/900000000000441003)\
[900000000000442005 |Core metadata concept|](http://snomed.info/id/900000000000442005) ... (see previous table)\
[900000000000454005 |Foundation metadata concept|](http://snomed.info/id/900000000000454005)\
[900000000000455006 |Reference set|](http://snomed.info/id/900000000000455006)\
[900000000000516008 |Annotation type|](http://snomed.info/id/900000000000516008)\
[900000000000521006 |Association type|](http://snomed.info/id/900000000000521006)\
[900000000000480006 |Attribute value type|](http://snomed.info/id/900000000000480006)\
[705109006 |Code to expression type reference set|](http://snomed.info/id/705109006)\
[447250001 |Complex map type reference set|](http://snomed.info/id/447250001)\
[609430003 |Concept model reference set|](http://snomed.info/id/609430003)\
[900000000000538005 |Description format|](http://snomed.info/id/900000000000538005)\
[733614007 |Expansion history reference set|](http://snomed.info/id/733614007)\
[609331003 |Extended map type reference set|](http://snomed.info/id/609331003)\
[733613001 |Intensional definition reference set|](http://snomed.info/id/733613001)\
[900000000000506000 |Language type|](http://snomed.info/id/900000000000506000)\
[705111002 |Map correlation and origin type reference set|](http://snomed.info/id/705111002)\
[900000000000534007 |Module dependency|](http://snomed.info/id/900000000000534007)\
[723564002 |MRCM reference set|](http://snomed.info/id/723564002)\
[733618005 |Ordered association type reference set|](http://snomed.info/id/733618005)\
[733619002 |Ordered component type reference set|](http://snomed.info/id/733619002)\
[447258008 |Ordered type reference set|](http://snomed.info/id/447258008)\
[900000000000512005 |Query specification type|](http://snomed.info/id/900000000000512005)\
[900000000000456007 |Reference set descriptor|](http://snomed.info/id/900000000000456007)\
[900000000000496009 |Simple map|](http://snomed.info/id/900000000000496009)\
[446609009 |Simple type reference set|](http://snomed.info/id/446609009)\
[900000000000457003 |Reference set attribute|](http://snomed.info/id/900000000000457003)\
[447257003 |"Linked to" reference set attribute|](http://snomed.info/id/447257003)\
[900000000000511003 |Acceptability|](http://snomed.info/id/900000000000511003)\
...\
[723569007 |Template|](http://snomed.info/id/723569007)\
[106237007 |Linkage concept|](http://snomed.info/id/106237007)\
[246061005 |Attribute|](http://snomed.info/id/246061005)\
[410663007 |Concept history attribute|](http://snomed.info/id/410663007)\
[410662002 |Concept model attribute|](http://snomed.info/id/410662002)\
[116680003 |Is a|](http://snomed.info/id/116680003)\
[408739003 |Unapproved attribute|](http://snomed.info/id/408739003)\
[416698001 |Link assertion|](http://snomed.info/id/416698001)\
[417151001 |Has explanation|](http://snomed.info/id/417151001)\
...\
[416872009 |Is etiology for|](http://snomed.info/id/416872009)\
[417318003 |Is manifestation of|](http://snomed.info/id/417318003)\
[370136006 |Namespace concept|](http://snomed.info/id/370136006)\
[373872000 |Core Namespace|](http://snomed.info/id/373872000)\
[370137002 |Extension Namespace 1000000|](http://snomed.info/id/370137002)\
...\
[713754005 |Extension Namespace 1000999|](http://snomed.info/id/713754005)

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