Authoring descriptions in an extension may involve creating new descriptions, inactivating descriptions or modifying descriptions.

Modify Description in an Extension

Purpose

The main reasons for modifying a description in an extension are:

• The description term contains an error that needs fixing

• The case significance of the term needs to be changed

• The acceptability of the description has changed - e.g. from acceptable to preferred, or from preferred to acceptable.

Principles

Overview

Making changes to existing descriptions requires careful consideration, because the descriptions may have been used in clinical records to represent the meaning of the associated concept. Changes are, however, permitted, as long as only mutable attributes are modified. Immutable attribute values should not be modified.

The conceptId field, the languageCode field and the typeId field cannot change between different versions of the same description. If a change is required to one of these immutable attributes, then the existing description should be inactivated, and a new description with the required attribute values should will be added.

Extension producers should not modify descriptions, which are part of the International Edition. When issues with international descriptions arise, SNOMED International should be notified so the issue may be addressed in a subsequent release.

The table below lists the various description attributes and their mutability. The following modifications to the mutable attributes are permitted

• Changing the active attribute to 0 (i.e. inactive). For more information, please refer to .

• Changing the term of the description. Please note that only limited changes may be made to the term field, as defined by editorial rules.

  • The International SNOMED CT Editorial Guide states when making a minor change to an FSN, a new description must be created and the old description must be inactivated.

Table: Mutability of description attributes

An extension producer may also need to change the acceptability of a description. For example, a synonym may change from being acceptable to preferred, or from being preferred to acceptable. This type of change does not require any modifications to the Description file. Instead, the associated member of the relevant language reference set must be modified. For more information, please refer to .

The table below provides a summary of the process to follow when modifying descriptions in an extension.

Purpose

The main reasons for adding descriptions in an extension are:

• To translate SNOMED CT into another language

• To add terms that are preferred or accepted within a local setting, for example

  • Common clinical terms that facilitate searching for concepts

  • Patient friendly terms

• To support the creation of new concepts in the extension, which each require at least two descriptions

As depicted in the image below, a description in an extension may refer to any concept in the same extension (Extension B), any concept in a module upon which the extension modules depend (Extension A), or any concept in the International Edition.

Note that the green and orange triangles pointing to the purple circle represent a situation in which a description is added to an extension that describes an international concept. These extension descriptions supplement the descriptions that are already part of the International Edition.

Descriptions in SNOMED CT are represented in a description file. At least two descriptions must be created for each new concept in an extension:

• A description of type (FSN)

  • Note that all extension producers should create an unambiguous FSN in US English for each new concept. Additional FSNs may also be created to support other languages and dialects.

• A description of type , in either English or an alternative language

The acceptability of new descriptions must be specified in a language reference set.

The following principles apply to adding FSNs in an extension.

• There may be more than one active description with a typeId of (FSN).

  • However, only one FSN should be marked as preferred for use in a given language or dialect by a specific Language Reference Set.

• Every extension concept must have an unambiguous FSN in US English.

• Unlike FSNs, synonyms are not necessarily unique between concepts, as the same term can be used to describe more than one concept.

• The preferred term is the synonym marked as preferred for use in the Language Reference Set for a given language or dialect.

  • There must be at least one description with a typeId of and an acceptabilityId value of for each concept associated with a description in a given language reference set.

When a description is created in an extension, as part of a translation or to provide a localized synonym for an existing concept, a new row should be added in the relevant language reference set to indicate whether the description is or in the given language or dialect.

The table below provides a summary of the process to follow when adding new descriptions to an extension.

Inactivate Description in an Extension

Purpose

There are various reasons for inactivating descriptions in an extension, including:

• The description does not represent the same meaning as the fully specified name (FSN) of the concept

• The description is no longer current, useful, appropriate or acceptable

• The description fails to comply with the current editorial guidance. For more information, please refer to Terming and Naming Conventions in the Editorial Guide.

• The description contains a technical error, such as a typographic error

Descriptions created in an extension can be inactivated if necessary. This is done by inactivating both the description itself and the associated member(s) of the relevant language reference set(s). It is recommended that the reason for inactivation is specified in the see .

Descriptions which belong to the International Edition (or another module on which the extension depends) should not be inactivated in the extension. If there is a requirement to remove international descriptions from an extension, this should be accomplished by excluding the given description identifiers from the relevant language reference set(s). Two possible approaches for this are described below.

This approach involves creating a copy of one of the language reference sets distributed with the International Edition, and adding or removing members as required. All members of the new language reference set must be assigned to a module in the extension. When using this approach, the extension producer is responsible for maintaining the new language reference set. If the extension producer wants their new language reference set to incorporate future changes made to the international language reference set, they are responsible for maintaining these changes.

An extension producer may choose not to create a new copy of an international language reference set. Instead, they may use the international language reference set directly, and exclude any members of this reference set by inactivating the relevant members in their extension module. To exclude a description from an international language reference set, a new version of the reference set member is created with the following attributes:

• id is set to the same value as that of the member of the international language reference set

• effectiveTime is set to the release date of the extension * Note that this date should be after the effectiveTime of the reference set member in the international release

• active is set to '0' to indicate that the member is being inactived _ _

• moduleId

Please note that if a new version of the reference set member is published in the International Edition, this will become the current version of that member. It may, therefore be necessary to create a new inactive version in the extension with a more recent effectiveTime.

This table describes the process of excluding descriptions in an extension.