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Terminology and extension producers need tools to assist with the authoring process, and many of the authoring principles described in the following sections can be automatically validated. It is therefore important to consider these principles when establishing requirements for an authoring tool. Furthermore, an extension producer should be aware of these principles and ensure that the content they develop in their extension does not directly modify any components or derivatives in a module belonging to another organization, such as the International Edition of SNOMED CT.

General Authoring Principles

SNOMED CT has a set of general authoring principles which applies all components, for example:

  • Organizations may add, inactivate or modify components or derivatives which belong to modules they own
    • Additions or changes to components and derivatives which belong to modules maintained by SNOMED International or other organizations must be avoided
      • The enumerated values used in RF2 components which form part of an extension must be all be represented by metadata concepts. These concepts may belong to modules in the International Edition, modules which belong to another extension producer, or modules owned by the extension producer. Please refer to concept enumerations in the Terminology Services Guide for more information about concept enumerations
    • Components which belong to modules in the International Edition or modules which belong to another extension producer, can be inactivated using reference sets which specify components for exclusion 
    • Consider the mutability of component attributes to determine which changes are permissible when modifying components which belong to modules in the International Edition or modules which belong to another extension producer
  • Issues with International Edition which impact content in an extension should be raised using a content request

Module Assignment

As indicated in, extension producers should assign any terminology content they create to a module which they manage. I.e. every concept, description, relationship or reference set member, which is managed within an extension should belong to the module of the extension producer. This is accomplished with the moduleId attribute. The moduleId makes clear that this component or reference set member is currently maintained as part of the extension module. It also indicates that this component or reference set member may depend on the content of other modules (including modules from the International Edition) as specified in the module dependency reference set.

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The following sections present key principles for authoring components and reference sets within an extension. 

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Please note that this section is not intended to teach how clinical content is authored. Clinical content is authored in accordance with editorial rules. For more information, please refer to the Editorial Guide.