derivative

This is a synonym for SNOMED CT derivative.

SNOMED CT derivative

A document, subset, set of maps, or other resource that includes references to, or is derived from, one or more SNOMED CT components.

Notes

• The standard computer processable representation for most types of SNOMED CT derivatives is a reference set.

• The SNOMED CT Affiliate License agreement contains a more specific legal definition of the term "Derivative".

Alternatives

• Derivative

A process that generates a set of logically consistent inferences by applying description logic rules to the stated view of concept definitions.

• Automatic classification

A process that allows legacy data to be accessible in a system that uses SNOMED CT.

• Data migration allows retrieval and reuse of data that was recorded prior to the introduction of SNOMED CT. This may be accomplished through actual conversion of the data or provision of methods to access data in its original form.

description logic

A representation of semantic knowledge that allows formal reasoning to be applied based on axioms.

Notes

• Description logic definitions of SNOMED CT concepts are represented in two ways, as: * OWL Functional Syntax in an OWL Expression Reference Set * Defining relationships in the Relationship File.

• The formal rules of description logic can be applied to concept definitions by software tools (description logic classifiers) to interpret the meaning of concepts. This enables confirmation of the logical integrity of the terminology, and can also be used to support meaning-based retrieval from records containing SNOMED CT expressions or concepts.

Alternatives

• DL

DNF

An abbreviation for the now obsolete "distribution normal form" replaced by necessary normal form.

necessary normal form

An inferred view of a concept definition that includes only defining relationships that are necessarily true.

Notes

• The necessary normal form is designed to represent an inferred view derived from the enhanced concept definitions in a form that can be distributed in the relationship file. Although the enhanced features cannot be fully represented within the structure of the relationship file, the necessary normal form provides a view of the results of classifying data that is accessible to those without access to description logic tools.

Change Notices

• Changes introduced in the July 2019 release of the International Edition, enhanced the ability of SNOMED CT to support more advanced description logic. These changes allow the stated view of concept definitions to use axioms represent using the OWL Functional Syntax.

Alternatives

• NNF

• Distribution normal form - obsolete-definition

A concept that provides the value of a relationship.

• The destination concept is identified by the destinationId in the relationship.

• The destination concept __ represents the value of a defining characteristic of the source concept.

descendant

This is an abbreviation for subtype descendant.

subtype descendant

A concept that is a subtype of a specified concept.

Notes

• Includes the subtype children and the subtype children of each subtype child and so on recursively.

• The terms subtype and subtype descendant are synonymous. However, it is sometime helpful to use the term subtype descendant to emphasize inclusion of all subtypes not just subtype children.

Example

The figure below shows an example hierarchy in which concept C has eight subtype descendants (F, G, M, N, O, P, U and V).

• Descendant

description

This is an abbreviation for SNOMED CT description.

SNOMED CT description

An association between a human-readable phrase (term) and a particular SNOMED CT concept.

Notes

• Each description is represented by a separate row in the Description File.

• Each description has a unique identifier and connects a concept with a term of a specified description type. All concepts have descriptions with description types fully specified name and synonym. Other description type can be defined and may be applied to some concepts.

Alternatives

• Description

A view of SNOMED CT that contains only rows that represent changes to components and reference set members since a specified date or between two specified dates in the past.

• The delta view between the most recent release date and the immediately preceding release date matches the content of the most recent delta release.

• A full release can be filtered to provide delta views for the current release or between any two release dates in the past.

DAG

This is an abbreviation for directed acyclic graph.

directed acyclic graph

A set of nodes connected to one another by lines (edges) in which each connection has a specified direction such that no route that follows the direction of the connections enters a loop (cycle).

Notes

• The SNOMED CT subtype hierarchy is a Directed Acyclic Graph. SNOMED CT concepts are nodes and subtype relationships are the directed lines that connect them. All subtype relationships lead from a more specific concept to a more general concept, so a cycle would be a logical error (e.g. if "rubella virus" is a type of "virus" and "virus" is a type of "microorganism", then "microorganism" cannot be a type of "rubella virus").

Alternatives

• DAG

• Wikipedia

A field in the relationship release file containing a SNOMED CT identifier that represents the destination concept or attribute value of the associated relationship.

domain

This is an abbreviation for concept model domain.

concept model domain

A set of concepts which the concept model permits to be defined or refined, using a particular set of attributes and ranges.

Notes

• A domain to which an attribute can be applied typically includes concepts in one or more branches of the subtype hierarchy.

Examples

• Section Procedure Attributes Summary of the SNOMED CT Editorial Guide defines the domain , attributes and ranges for | Procedure| .

• The | Procedure| domain is defined as follows:

<< /* the concept "Procedure" or any of its subtypes */

• The table row below shows how | Procedure site| , one of the many attributes applicable to the | Procedure| domain, is specified together with its range of permitted values.

• Domain

distribution normal form - obsolete-definition

An inferred view of a concept definition from which redundant subtype relationships have been removed.

Notes

• The distribution normal form allows non-redundant subtype relationships to readily display a hierarchical view of the terminology.

• The distribution normal form was distributed in the SNOMED CT relationship file until July 2018.

Alternatives

• DNF

Data Creation System

A computer system that is used to create records or other data that is encoded with SNOMED CT.

Notes

• The above definition is copied from the Affiliate License Agreement.

• Data Creation Systems and Data Analysis Systems are fee-based in Non-Member Territories.

Provide Feedback

disjunctive

This is a synonym for disjunction.

disjunction

An operator used to assert that at least one of two (or more) parts of a concept definition or expression constraint must be true.

Notes

• Disjunction can be represented by theOR operator. A disjunction of A with B , means that either A OR B must be true.

• Disjunction gives the same result as an UNION between the set of concepts or expressions for which A is true and the set of concepts or expressions for which B is true.

• The following expression constraint is satisfied by clinical findings that are subtypes of either OR .

< OR <

defined concept

This is a synonym for sufficiently defined concept.

sufficiently defined concept

A concept with one or more sufficient definitions.

Notes

• A SNOMED CT concept is expressed in a human-readable form by its fully specified name (FSN).

• A sufficiently defined concept has at least one sufficient definition that distinguishes it from any concepts or expressions that are neither equivalent to, nor subtypes of, the defined concept.

Examples

• The concept is sufficiently defined by the following definition because any concept for which these defining relationships are true, is either the disorder appendicitis or a subtype of appendicitis.

=== : = , =

• Prior to July 2018, SNOMED CT could only support one sufficient definition for each concept could not represent the example above. A further limitation, that also prevented formal representation of that example was the stated relationship file was only able to represent necessary conditions.

• Changes introduced in the July 2018 release of the International Edition allow assertions to be represented as axioms in the OWL axiom reference set file. This will allow concepts to be defined by multiple sufficient definitions, some of which may contain assertions that are not necessarily true.

• Following these changes a concept will only be marked as sufficiently defined if it is sufficiently defined by relationships. However, the OWL axioms may provide a sufficient definition that cannot be fully represented as relationships.

• Fully defined concept

disjunction

An operator used to assert that at least one of two (or more) parts of a concept definition or expression constraint must be true.

Notes

• Disjunction can be represented by theOR operator. A disjunction of A with B , means that either A OR B must be true.

• Disjunction gives the same result as an UNION between the set of concepts or expressions for which A is true and the set of concepts or expressions for which B is true.

• The following expression constraint is satisfied by clinical findings that are subtypes of either OR .

< OR <

defining characteristic

This is a synonym for defining relationship.

defining relationship

A relationship to a target concept that is always necessarily true for any instance of the source concept.

Notes

• All defining relationships represent necessary conditions. However, some necessary conditions that can be represented by OWL Axioms cannot be represented by relationships.

Example

• The defining relationships of the concept 53442002 | gastrectomy| include

  • = and

  • = .

• Defining characteristic

distribution normal form

Replaced in 2019 by the [necessary normal form](https://confluence.ihtsdotools.org/display/DOCGLOSS/necessary normal form "Glossary link: necessary normal form").

necessary normal form

An inferred view of a concept definition that includes only defining relationships that are necessarily true.

Notes

• The necessary normal form is designed to represent an inferred view derived from the enhanced concept definitions in a form that can be distributed in the relationship file. Although the enhanced features cannot be fully represented within the structure of the relationship file, the necessary normal form provides a view of the results of classifying data that is accessible to those without access to description logic tools.

Change Notices

• Changes introduced in the July 2019 release of the International Edition, enhanced the ability of SNOMED CT to support more advanced description logic. These changes allow the stated view of concept definitions to use axioms represent using the OWL Functional Syntax.

• NNF

description identifier

A SNOMED CT identifier that uniquely identifies a description.

Provide Feedback

delta release

A release type in which the release files contain only rows that represent component versions and reference set member versions created since the previous release date.

Notes

• Each row in a delta release file represents either a new component or reference set member, or a change to an existing component or reference set member since the previous release date.

• A delta release identifies differences between two versions of the same release package.

• A delta release added to the previous full release is identical to the full release of the new version.

• The previous release date , on which a delta release is based, is usually the date of the most recent previous release. However, that may not always be the case. For example, where interim releases are made between two major releases there may be a combined delta release covering a period since a previous major release .

Please note :

• Delta files have been removed from the SNOMED International release package, Managed Service Extensions and Derivative packages. However a Delta Generation Tool is available for those who need it. The Delta Generation Tool allows users to create their own Delta between two fixed release dates - you can find it here:

description type

An indication of the intended use of a term of a SNOMED CT description when applied to the associated concept.

Notes

• The description type is represented by the value of the description.typeId attribute.

• Permitted values include the following (other types may be defined in future):

| synonym * A word or phrase that expresses the meaning of a SNOMED CT concept in a specified language. | textual definition * A narrative text explanation of the meaning of a concept that may exceed the maximum permitted length for a fully specified name.

Draft Standard for Trial Use

A specification and process to allow implementers to test a standard.

Notes

• At the end of the trial period, the standard may be balloted, revised, or withdrawn.

Example

• TermInfo, the joint project between HL7 International and SNOMED International, is an example of an HL7 DSTU.

Alternatives

• DSTU

DSTU

This is an abbreviation for Draft Standard for Trial Use.

Draft Standard for Trial Use

A specification and process to allow implementers to test a standard.

Notes

• At the end of the trial period, the standard may be balloted, revised, or withdrawn.

Example

• TermInfo, the joint project between HL7 International and SNOMED International, is an example of an HL7 DSTU.

Alternatives

• DSTU

A modification of the language of a particular geography or culture by means of the vocabulary and grammatical conventions applied to it.

• English has British and American dialects.

A computer system that is used to analyze records or other data that is encoded using SNOMED CT, but not if that system is also a Data Creation System.

Notes

• The above definition is copied from the Affiliate License Agreement.

• Data Analysis Systems and Data Creation Systems are fee-based in Non-Member Territories.

DL

This is an abbreviation for description logic.

description logic

A representation of semantic knowledge that allows formal reasoning to be applied based on axioms.

Notes

• Description logic definitions of SNOMED CT concepts are represented in two ways, as: * OWL Functional Syntax in an OWL Expression Reference Set * Defining relationships in the Relationship File.

• The formal rules of description logic can be applied to concept definitions by software tools (description logic classifiers) to interpret the meaning of concepts. This enables confirmation of the logical integrity of the terminology, and can also be used to support meaning-based retrieval from records containing SNOMED CT expressions or concepts.

Alternatives

• DL

• Wikipedia

defining relationship

A relationship to a target concept that is always necessarily true for any instance of the source concept.

Notes

• All defining relationships represent necessary conditions. However, some necessary conditions that can be represented by OWL Axioms cannot be represented by relationships.

Example

• The defining relationships of the concept 53442002 | gastrectomy| include

  • = and

  • = .

• Defining characteristic

A set of one or more rules that define which concepts are members of specific concept model domain.

• Domain constraints are specified using expression constraint language.

• A concept model domain is a set of concepts which the concept model permits to be defined or refined, using a particular set of attributes and ranges.

.

A term that occurs in more than one active description.

• Duplicate terms are valid as synonyms since these terms enable clinicians to use of familiar terms to find or express concepts.

• Duplicate terms are not valid as fully specified names, as these terms represent the unique formal name of each concept.

directed acyclic graph

A set of nodes connected to one another by lines (edges) in which each connection has a specified direction such that no route that follows the direction of the connections enters a loop (cycle).

Notes

• The SNOMED CT subtype hierarchy is a Directed Acyclic Graph. SNOMED CT concepts are nodes and subtype relationships are the directed lines that connect them. All subtype relationships lead from a more specific concept to a more general concept, so a cycle would be a logical error (e.g. if "rubella virus" is a type of "virus" and "virus" is a type of "microorganism", then "microorganism" cannot be a type of "rubella virus").

Alternatives

• DAG

Related Links

• Wikipedia

description logic classifier

A software tool that applies the rules of description logic to a set of axioms to infer additional relationships between concepts.

Notes

• SNOMED CT concept definitions are processed by a description logic classifier to generate inferred subtype hierarchies.

• SNOMED CT expressions can also be processed by a description logic classifier to make inferences that enable more complete and precise selective retrieval to support analytics.

Alternatives

• Classifier