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• How the MRCM will be authored and quality checked;,
• How the MRCM will be used to support the use cases described in Chapter 2;. Use Cases,
• How the MRCM will be versioned when corrections or enhancements are made; , and
• How the MRCM can be extended and adapted for use with SNOMED CT extensions;

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• .

Authoring and Quality Checks

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To support implementers who prefer to process string-based representations of the rules, three MRCM attributes have been provided that concatenate information from other fields (as per the table below). These attributes have been populated automatically (rather than authored manually) to avoid inconsistencies between the structural and string-based representations of the rules.   The MRCM attributes that may be generated from other attributes are:

723589008|MRCM domain reference set|

111115723589008|MRCM domain reference set|

111115723604009|MRCM attribute domain reference set|

111115723592007|MRCM attribute range reference set|

723589008|MRCM domain reference set|

723592007|MRCM attribute range reference set|

In addition, the quality of the international SNOMED CT MRCM is expected to be checked using the following mechanisms:

• Manual review, supported by the inclusion of human-readable terms for each concept identifier in the reference sets;
• Automated testing, including checks for the following:
  • All MRCM reference sets conform to the associated Descriptor Template;,
  • All concept identifiers refer to active concepts in the relevant SNOMED CT international edition; ,
  • All concept identifiers refer to concepts from a value set appropriate for that field;,
  • All parsable strings (e.g. expression constraints) are syntactically valid (based on the associated ABNF syntax) and refer to concepts that are active in the relevant SNOMED CT international edition; ,
• Feedback from direct use by IHTSDO SNOMED International staff in the SNOMED CT authoring tools;, and
• Feedback from the SNOMED CT member, vendor and user communities.

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Another important consideration in the design of the MRCM is how it can best be used to support the range of anticipated use cases. In the following this section, we describe the ways in which the MRCM design supports each of the use cases presented in Chapter 2. Use Cases.

Precoordinated Content Development

As described in Section 2. 2Use Cases, one of the key use cases for the SNOMED CT MRCM is to assist in with the consistent authoring and validation of SNOMED CT concepts. With this in mind, the following features were included to optimize the MRCM for use in precoordinated content development:

• The

  Scg expression
  ShowParts term
  111115723589008|MRCM domain reference set|

   and the

  Scg expression
  ShowParts term
  111115723604009|MRCM attribute domain reference set|

   include attribute domains defined in terms of the lowest common supertype permitted in the inferred view (i.e. after classification of the concept being authored);

• The

  Scg expression
  ShowParts term
  111115723589008|MRCM domain reference set|

   includes the proximal primitive constraints and mandatory defining relationships required to support proximal primitive modelling in each domain (in the stated view);

• The

  Scg expression
  ShowParts term
  111115723589008|MRCM domain reference set|

   includes a general domain template, which can be used for authoring any content in the given domain using either proximal primitive modelling or proximal parent modelling authoring methods. Please note that this general domain template may be further constrained to support the specialized modelling requirements of specific subhierarchies in the given domain.

• The

  Scg expression
  ShowParts term
  111115723589008|MRCM domain reference set|

   and the

  Scg expression
  ShowParts term
  111115723604009|MRCM attribute domain reference set|

   use domains defined in terms of a single top-level hierarchy. This enables concepts being authored to be tested for subsumption with each domain concept, using techniques that are relatively simple to implement (e.g. using a transitive closure table).

• The

  Scg expression
  ShowParts term
  111115723592007|MRCM attribute range reference set|

   specifies the valid set of values (rangeConstraint) for each attribute used in the authoring of precoordinated content.

• The

  Scg expression
  ShowParts term
  111115723592007|MRCM attribute range reference set|

   also includes a set of attribute rules that incorporate the domain, grouping, cardinality and range constraints together into an expression constraint, to support the efficient implementation of content validation.

• The ruleStrengthId attribute in the

  Scg expression
  ShowParts term
  111115723604009|MRCM attribute domain reference set|

   and the

  Scg expression
  ShowParts term
  111115723592007|MRCM attribute range reference set|

   allows both mandatory rules (resulting in errors) and optional rules (resulting in warnings) to be specified.

• The contentTypeId attribute in the

  Scg expression
  ShowParts term
  111115723604009|MRCM attribute domain reference set|

   and the

  Scg expression
  ShowParts term
  111115723592007|MRCM attribute range reference set|

   allows the scope of each rule to be restricted to a particular type of SNOMED CT content, including:

  • Scg expression
    ShowParts term
    723596005|All SNOMED CT content|

    – for rules which apply to both precoordinated and postcoordinated content;

  • Scg expression
    ShowParts term
    723594008|All precoordinated SNOMED CT content|

    – for rules which apply to all precoordinated content (but not necessarily to postcoordinated content);

  • Scg expression
    ShowParts term
    723593002|All new precoordinated SNOMED CT content|

    New precoordinated SNOMED CT content only

    – for rules which apply to newly authored precoordinated content, which may not necessarily be valid for all existing content; and

  • Scg expression
    ShowParts term
    723595009|All postcoordinated SNOMED CT content|

    – for rules which apply to all postcoordinated content (but not necessarily to precoordinated content).

Expressions, Constraints and Queries

Section 2. 3 Use Cases describes using the SNOMED CT MRCM to assist the authoring and validation of SNOMED CT postcoordinated expressions, SNOMED CT expression constraints, and SNOMED CT queries. These languages allow one or more focus concepts to be defined, which when tested against a domain in the MRCM enables possible attribute refinements, cardinalities and valid ranges to be found.

The optimizations described in section 6.3.1 above for use in SNOMED CT concept authoring, can also make the authoring and validation of SNOMED CT expressions, expression constraints and queries more efficient. In addition to these general authoring features, the

111115723589008|MRCM domain reference set|

111115723592007|MRCM attribute range reference set|

Please note that SNOMED CT expression constraints and queries used on a substrate that includes only precoordinated content must use the MRCM rules that apply to

111115723596005|All SNOMED CT content|

111115723594008|All precoordinated SNOMED CT content|

111115723595009|All postcoordinated SNOMED CT content|

111115723596005|All SNOMED CT content|

111115723604009|MRCM attribute domain reference set|

Natural Language Processing

In a similar way to how the MRCM can be used for postcoordinated expression authoring, the MRCM can The MRCM can also be used to support Natural Language Processing (NLP), as described in section 2. 4Use Cases. When terms used in the free text are associated with a particular SNOMED CT concept, this concept can be tested for subsumption against the domains in the

111115723589008|MRCM domain reference set|

111115723604009|MRCM attribute domain reference set|

111115723592007|MRCM attribute range reference set|

...

Terminology Binding to Information Models

Section 2. 5 describes Use Cases describes using the MRCM to suggest possible SNOMED CT terminology bindings for an information model, to ensure that the bindings are consistent (at least at a high level) with the SNOMED CT concept model, and to support the design of expression templates.

The features designed to support SNOMED CT content authoring can similarly be used to support these terminology binding purposes. For example, the domainTemplateForPostcoordination could be adopted and specialized to support the terminology binding requirements of a specific information model. Similarly, new use - case specific MRCM reference sets could be developed, which restrict the available attributes and ranges that may be used in a specific implementation scenario.

Versioning

As mentioned in Requirement 3. Requirements (D.5), the concept model must be able to be changed between releases to fix identified issues and enhance future releases.

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When a new or updated rule is introduced to the MRCM, it may take a period of time before all existing content conforms to the new rule. In these situations, a content type of

111115723593002|NewAll new precoordinated SNOMED CT content only|

111115723594008|All precoordinated SNOMED CT content|

111115723596005|All SNOMED CT content|

Extension

As described in Requirement 3. Requirements (D.6), the international MRCM rules defined by the IHTSDO SNOMED International must be able to be extended and adapted by organizations developing SNOMED CT extensions, to support the concept model requirements of their extension content.
To support this requirement, SNOMED CT extension developers will be able to copy the international MRCM rules defined by the IHTSDO SNOMED International into one or more extension MRCM reference sets and edit these reference sets to add new rules and restrict or extend the existing rules as required. New MRCM reference sets created for a SNOMED CT extension must be designed to ensure consistency and data integrity between editions. Please note that if no changes to the SNOMED CT concept model are required to support an extension, no additional MRCM reference sets need to be created, as the international MRCM can be reused by the extension.

The

111115723563008|MRCM Module Scope Reference Set|

111115723563008|MRCM Module Scope Reference Set|

...