This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.
Key requirements that drive the design, development, and maintenance of SNOMED CT are as follows. They are related to:
Electronic health applications (most often electronic health records or EHRs)
Support for effective delivery of high quality healthcare to individuals and populations
The terminology
Implementation and migration
The intended user communities
International, multilingual applicability
Supporting particular localities
National and strategic priorities
These requirements are interrelated. The design objective is to enable all user communities to realize the potential benefits. However, the needs of different user communities may vary. To meet the overall objectives, the design must consider the entire range of needs. The approach must also be scalable in order to enable extension to new user communities.
This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.
A terminological resource is only one part of an electronic health application. Implementation of SNOMED CT should support applications in meeting user needs, rather than adding a burden to development.
The functions required to implement a terminology can be divided into those that are:
Performed without reference to data stored in a particular application record structure.
Involved in storing, retrieving, or processing application data.
Applications may make use of different aspects of SNOMED CT. Some may require SNOMED CT for a very limited range of uses for which there may be minimal value. These applications may not require all the functions for a full implementation or all the concepts and codes in SNOMED CT.
There may be a general benefit in consistency with other more terminology rich applications.
A substantial body of clinical information may already be present in an electronic health application. Much of this information is represented using existing coding schemes, terminologies, and classifications. This information may be of value to individual patient records or to populations. Similarly, there are many queries and decision support protocols that contain information based on existing terminologies.
A new terminology should make provisions for the continuing use of information stored in records, queries, and protocols represented by other terminologies. There are two general approaches to this:
Conversion of legacy data into a form consistent with SNOMED CT.
Allowing legacy and SNOMED CT data to coexist. Legacy codes must be recognizably different from SNOMED CT codes. In addition, the relationship between codes in SNOMED CT and legacy codes must be recognized when retrieving data.
Information represented with SNOMED CT codes must be reliable and reproducible. This means:
The meaning of a code should not change over time.
Information should be reproducible independent of the application.
The query of codes should be reliable. This means:
There should be complete recall, including specific, more detailed codes and expressions subsumed by general codes and expressions in the query.
There should be specificity and precision excluding codes and expressions that are not subsumed by the codes and expressions in the query.
The effects of the following should be taken into account:
Precoordinated relationships between codes in records or queries.
Postcoordinated qualifications applied to codes or expressions in records or queries.
Relationships between codes and other contextual information implied by the record structure.
This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.
The anticipated benefits of SNOMED CT are derived from use of information to support effective delivery of high quality healthcare to individuals and populations.
Clinically relevant information in an electronic health record acts as an aide-memoire for the clinician, enabling recall of previous interactions.
Structured data entry enhances the value of an electronic health record in various ways. It may:
Simplify recording of frequently collected data
Ensure that information is collected in a reliable and reproducible way
Help clinicians to think logically about a patient's condition
Clinical applications may combine several data entry methods. Some of the most commonly used methods are as follows:
Searching a coded terminology for matching terms using words or phrases
Navigating a hierarchical structure to refine or generalize meanings
Using templates or protocols to record structured information; may be based on answers to questions or values entered on a data entry form
Parsing of natural language to identify and retrospectively code and structure data
Data entry may require selection from a list. Such lists must be manageable in size and appropriate to the needs of the user.
A multilingual, multidisciplinary terminology requires mechanisms that limit and/or prioritize access to terms and codes in ways that are appropriate to:
Languages and dialects
Countries, organizations, disciplines, specialties, and users
Contexts within a record or protocol
When a code is entered in a record it may require structured entry of additional qualifying information.
Qualifying information may be coded.
For example,
The code named removal of kidney may require a statement of laterality.
Qualifying information may be numeric.
To meet all the needs for coded structured data entry in a health record, a terminology must have an adequate scope.
The main body of SNOMED CT covers the required scope.
It may be difficult to meet the needs of some organizations, specialties, and users; they may need specific terms or codes to meet their own operational requirements. Therefore, SNOMED CT is structured to allow for additions to meet specific needs.
A clinical terminology requires frequent changes including new codes, terms, and relationships between codes. Changes may be required due to new:
Health risks
Health and disease process information
Drugs, investigations, therapies, and procedures
The presentation of clinical information may:
Highlight key information and indicate links between items, thus helping clinicians understand patients' conditions.
Be determined entirely by record structure without regard to the terminological resource (e.g.,may be in chronological order, by author, or by the type of recorded event).
Be enhanced based on its semantic content (e.g., grouping procedures, investigation results, or observations relevant to a particular disease process).
Interfaces between recorded clinical information and appropriate decision support tools and reference works may assist the clinician in selecting diagnostic tests, making diagnoses, and choosing treatment. Decision support requires selective retrieval and processing of information in an individual health record to determine whether the patient has particular characteristics relevant to the decision support protocol. The algorithms for establishing the presence of characteristics should include relationships between coded meanings and other aspects of record structure. Performance is also important, as decision support algorithms are typically run in real-time during data recording. Decision support algorithms may:
Depend on numeric or other values (and their units) associated with particular observations
Include the context in which information is recorded, e.g., the date of recording and any stated relationships between individual items of information
Include information such as age, sex, clinical conditions, findings, surgical procedures, medication, and social/environmental factors, such as occupation
Use codes or identifiers from other terminologies, classifications, or proprietary schemes. Mapping tables are required to allow applications that use a terminology to interface with these resources
Effective delivery of high quality healthcare to individuals requires communication between those involved in providing care. This requires communication within and across teams or organizations.
The primary objective of many clinical communications is to convey information from human to human. Communications with this purpose should include human-readable text. Relying on text from coded data is not recommended. Coded data is therefore not relevant to the requirement for human-to-human communication.
A receiving application may process clinical communications. This information may need to be retrieved and processed to meet terminology requirements. To meet terminology requirements, messages and other means of electronic communication must permit the communication of SNOMED CT identifiers and associated structures.
Communication specifications, such as those produced by HL7 and CENTC251, define the structures to meet requirements. The coded information is used in two distinct situations:
Coded elements that must be filled with codes enumerated in the specifications. The codes enumerated in the specifications generally communicate, mission critical features of the message. Some of the enumerated codes and the codes in a clinical terminology may have overlapping meanings.
Coded elements that are populated with clinical codes from appropriate coding schemes. The open coded elements may require the full expressiveness of a terminology. Some of the open coded elements may be restricted to codes that express particular types of meaning.
For example,
There are two situations in which communication of coded information may be of value for human-to-human communication. They are where:
The storage capacity or communication bandwidth is restricted. Receiving applications must contain (or have real-time access to) a table listing the text description associated with each code.
The translation between the languages of the sender and the recipient is needed. A coded representation of a meaning may allow the appropriate description in the recipient's language.
Recording a particular code may trigger a communication. And, receipt of a code, may trigger specific processing in the receiving application.
For example,
Recording a decision to prescribe a medicine might trigger an electronic prescription sent to the pharmacy. Receipt of such a prescription might trigger dispensing and stocking activities.
The relationship of a trigger is an additional characteristic of a code that may be context dependent.
Patients may wish to view, and comprehend, their own records. For SNOMED CT to meet this requirement, the inclusion of patient-friendly terms should be considered. However, this requirement should not take precedence over accurate professional terminology.
Patients may also be allowed to contribute to their own records, i.e., be users of SNOMED CT.
For example,
Patients with diabetes may monitor and record their blood glucose levels.
The provision of effective high-quality care to populations requires an understanding of the state of health and healthcare needs of that population. Information recorded about individual patients must be available for analysis to determine trends.
It must be possible to analyze data recorded with SNOMED CT.
Population trends are usually monitored at a higher level, using codes that are more general than those used in individual patient records. This may be accomplished through one or both of the following methods:
Using hierarchical relationships and/or equivalences defined within SNOMED CT.
Mapping SNOMED CT codes to codes in appropriate classifications.
Appropriate analysis of information requires reliable and reproducible queries.
The scope of SNOMED CT must cover the types of information relevant to analysis.
Analysis may require data about multiple clinical characteristics. Queries must account for both the terminology and the record structure.
The requirements for analysis of quality of service are similar to those for analysis of health needs. The main difference is that the scope of the analysis must be extended to cover consultations, referrals, procedures, medications, and other interventions.
The requirements for research are also similar to those for analysis of health needs, however, there is a need to allow for:
Recording interventions in ways that do not compromise blind and double blind trials.
Adding SNOMED CT content for experimental observations or treatments, which may never require permanent addition to the terminology.
The management and funding of healthcare delivery often depends on recording and reporting of particular information, e.g. bundled or packaged care. Automating this process offers a way of reducing bureaucratic overhead, i.e. mapping clinical information recorded with SNOMED CT to appropriate forms.
Some information required for management and funding purposes is specifically related to claims for particular events or services.
For example,
Funding general practitioners in the NHS is dependent on meeting immunization administration and cervical cytology screening targets.
The scope of SNOMED CT must be adequate to meet these needs, or must be capable of extension to meet these needs, without presenting irrelevant terms or coded meanings to those not requiring them.
Organizations, such as WHO and some government bodies, require specific data related to healthcare statistics. Organizations should be able to use clinical information recorded with SNOMED CT. When this is not possible, the clinical information should at least support their manual generation. Using structured data entry allows for direct mapping to statutory national and international classifications such as ICD, CPT, OPC, etc.
Population-based preventive care should be offered to specific groups, based on sex, age, medical history, and other factors. Health information applications based on information recorded with SNOMED CT can be used to identify patients, so they can be offered appropriate care.
This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.
The headings in this section are the requirements identified in Desiderata for Controlled Medical Vocabularies in the Twenty-First Century by J.J. Cimino published in Methods of Information in Medicine 1998:37:394-403. Following each, is an explanation of the way in which SNOMED CT meets the requirement.
SNOMED CT content must be adequate both in scope and quality and must:
Cover a wide variety of domains and different organizational needs, clinical disciplines, and medical specialties
Meet the needs of an expanding scope, while retaining quality, with a structured systematic approach
Codes must have one meaning (nonvagueness) and no more than one meaning (nonambiguity). These characteristics are sometimes called concept orientation , but SNOMED CT deprecates the use of the word concept to describe codes or their meanings.
A code and its meaning may be expressed by more than one term. The terms vary between languages and dialects. In any language or dialect there may be several synonymous terms.
Once assigned a meaning, a code must not change its meaning. Refinements, due to changes in the state of knowledge, may lead to inactivation of codes from SNOMED CT. An inactivated code may be replaced by a new, more precisely defined code.
The structure of an identifier (code) should not contain any semantic information about its meaning or relationships.
SNOMED CT supports multiple hierarchies. A code may have more than one hierarchical parent and various paths to its root code.
When possible, the meaning of codes should be formally defined by relationships to other codes.
Codes with the phrase, not elsewhere classified , are not allowed in SNOMED CT. However, many classifications contain terms with this phrase. A term with not elsewhere classified includes general variants that are not specifically represented. The meaning of such a code may change over time. As codes with more specific meanings are added, this narrows the codes included in the not elsewhere classified codes.
Different users will need to express more or less finely granular meanings. SNOMED CT:
Must accommodate a wide range of levels of detail
Must recognize the relationships between meanings at different levels of granularity
Should allow selection of codes that include navigation to other codes with more or less finely grained meaning
May need to restrict the levels of granularity used in different applications or in different contexts within the same application
The view of a code's meaning, with multiple hierarchical parents, should not depend on reaching it by following the hierarchy from a particular parent.
The meaning of a code in a patient record may be altered by its context. Standards for patient record architectures and modeled healthcare communication are changing. The role of SNOMED CT in the context of these structures should be evaluated and appropriate recommendations made.
Terminologies need to change over time. SNOMED CT should implement these changes in ways that are well-documented and tracked and that provide a path for systems and users.
The same information can often be coded in different ways. A controlled terminology, that has an adequate scope, cannot exclude this possibility. Instead it should facilitate recognition of equivalent terms.
This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.
The terms required by users of a clinical terminology vary according to the local languages and dialects.
When using a terminology, users must see terms in a language and dialect with which they are familiar. The terms must be clear and unambiguous independent of any hierarchical context or formal definition.
The display of terms must not be confused by inclusion of terms in other languages or dialects.
Typing, speech recognition, and document scanning
To display a code's description in a list that has not been derived from a text search, the term must be intelligible and appropriate to the user.
For example,
The code named hemoglobin measurement may enable entry of a numeric value expressed in a substance concentration.
HL7 requires that coding schemes meet certain criteria, one of which is the ability to express limited subsets of codes appropriate to particular elements.
The terms used in different languages and dialects are not mutually exclusive. A term may be common to several languages or dialects of a language.
When a code is presented without a specific reference to a term, an appropriate preferred term should be displayed. A term may be a preferred term in one dialect and a synonym in another.
Some terms differ only in spelling conventions (e.g. color vs. colour). The same spelling variants may recur in many different terms.
It may be appropriate to recognize these cases and handle them differently from other term variants.
An individual instantiation of an application may only require access to a single language or dialect. It is inappropriate to install and maintain all language and dialect variants.
An application may need to support several languages with the ability to switch between languages and dialects in real-time to meet the needs of users.
Some specialties or disciplines prefer to use different terms to describe the same meaning. A particular specialist may use a precise term, while a generalist may use a different term to describe the same condition.
The following table lists factors affecting term use and examples of each.
Geographic and seasonal differences
Malaria is more common in certain regions. Hay fever is more common in spring, summer, and fall.
Cultural perceptions of health
Acceptance of alternative therapies
Discipline or specialty
Particular terms may be specific to an organization. They may not be included in the International Release of SNOMED CT. Organizations and users must be able to add terms or codes to SNOMED CT, without devaluing the main body of SNOMED CT.
It may be necessary to combine several subsets and extensions to meet the needs of a country, an organization, or a specialty. There must be consistent rules for combining subsets and extensions.
The requirements of a particular user may change according to the role they are performing. A single instance of an application may need to support different requirements of several users.
Obstetricians use fundus to mean fundus of the uterus; gastroenterologists use the same term to mean fundus of the stomach.
Surgeons record operative procedures relevant to their specialties
Professional criteria
The definition of hypertension may vary based on professional guidelines
National or organizational requirements, including those for administrative or funding purposes
Performance measure results affecting reimbursement
Topics of special interest to individual clinicians
Infectious disease specialist with an interest in tropical diseases
This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.
A summary of the SNOMED CT requirements is as follows. Additional information may be found throughout this guide, as well as in other documents on the SNOMED International website.
Coded meaning
Not Elsewhere Classified (NEC); Not Otherwise Specified (NOS)
Codes with not elsewhere classified or not otherwise specified must be inactivated and no new ones may be added
Extension
Allows extensions to the main body of work
Extensions are distinguishable from components of the main body; should be traceable to a responsible organization
Allows for distinguishing and tracing the code source or identifier used in patient records
Combinations
Include consistent rules for combining subsets to meet the requirements of users
Distribution and Installation
Subsets are distributed in a format that is readily usable by system developers. The format is fully specified and does not vary from release to release. The distribution format allows:
Subsets to be installed separately
Related or interdependent subsets to be selected and installed as groups
Configuration
It is possible to configure an application to use a particular subset or combination of subsets; changing configurations does not require reinstallation
Qualifying Characteristics
Enables a code recorded in a patient record to be qualified by adding relevant qualifying characteristics
Each qualifying characteristic is itself a code with a specified relationship to a qualified code
Specifies possible qualifying characteristics for each code or for a group of related codes (e.g. an anatomical site could be added to the code named osteoarthrosis )
Kind-of-Value
Enables codes to be qualified by the addition of relevant values
Specifies the types of values that can be added to particular codes (e.g. a substance concentration value can be added to the code named hemoglobin concentration )
Additional Characteristics
Is able to assert other characteristics of a code that may be time- or context-dependent (e.g. new medical information may require updates to some codes)
Presentation
Enables the consistent and reproducible storage of information, which is subsequently retrieved for presentation
Requirements are similar to those for decision support
Must be real-time, but usually involves filtering by broad categories of code; less precise than for decision support
Record Conversion
It should be possible to convert legacy data, based on early coding schemes (SNOMED, Read Codes, or NHS Clinical Terms), to SNOMED CT compatible forms. This is subject to medico-legal constraints
Migration of Terminology-Dependent Products
Projects in the UK NHS, that currently make use of Read Codes or NHS Clinical Terms, must plan migration to allow future use of SNOMED CT
Reference Works
Codes are used to establish links with decisions-support protocols or other references
Mapping between these codes and reference sources may help to facilitate their use
The central component is coded meanings.
Each code must have a single clear and unambiguous meaning
Identifier
Components must have unique identifiers.
The internal structure of these identifiers must not imply the meaning or relationships of a code
Description
Represents the association between terms (text strings) and the meanings that they describe (may be language or dialect dependent)
Preferred Term
Represents the special association between each code and a preferred term (used to display the meaning, unless there is an alternative preference)
The preferred term association is language or dialect dependent
Fully Specified Name
Provides each code with a structured fully specified name that unambiguously describes its meaning
The fully specified name is defined in a reference language (the language of first use)
Translations of the fully specified name may also be required
Hierarchy
Represents hierarchical relationships between coded meanings
The form of representation allows a coded meaning to have multiple hierarchical parents (supertypes)
It guarantees that any alternative hierarchical view of a coded meaning is consistent
Relationship
Represents non-hierarchical relationships between coded meanings
Scope
The scope is adequate to meet the requirements of various countries, organizations, disciplines, and specialties
The extent to which the content requirements are covered develops over time
Updates
The content is regularly updated
Granularity
Distribution
Distributed in a format that is readily usable by application developers
This format is fully specified and is not changed from release to release
May be distributed for use with associated software, such as a browser
Persistence
The meaning of a code is persistent; It is not changed or deleted by updates
A code may be marked as inactivated when its meaning is found to be ambiguous, redundant or otherwise incorrect
Changes to the association between a concept and a code do not change or delete the description.
The description is marked as inactivated, and a new corrected description is created
History
Concepts
Includes a mechanism for representing subsets of concepts appropriate for a language, dialect, or specialty. It should allow:
Specification of the synonyms, preferred terms, and translated fully specified names in each language or dialect
Rational combination of languages and modification of language subsets to meet the needs of organizations or specialties
Codes
Includes mechanisms for representing subsets of codes for a country, organization, discipline, or specialty. The form of representation should allow:
An indication of the priority, or frequency of use
Rational combinations of subsets to meet the needs of users or groups of users
Specified Contexts
Navigating Relationships
Includes relationships that allow hierarchical navigation from a chosen code to a code that represents either a subtype or part of the chosen code
Supports navigation from a specific code to more general codes that represent a supertype of that code
Navigational concepts are not supported by SNOMED International
Aggregation of Related Codes
Includes relationships that allow aggregation of related codes to enable comprehensive and accurate retrieval from patient records
These relationships, together with appropriate history and cross-reference tables, enable the aggregation to include inactivated codes with similar or equivalent meanings
Defining Characteristics
Analysis
Enables the consistent and reproducible storage of information, which is subsequently retrieved for analysis; this requires retrieval that allows the inclusion of subtypes and equivalent codes to be included. Equivalent codes may include:
Codes represented in another (legacy) coding scheme
Redundant codes that were inactivated
Combinations of general codes and qualifying characteristics
Analysis usually requires retrieval of selected records from a population of patient records; usually performed in batch
Patient Review
Enables the consistent and reproducible storage of information, which is subsequently retrieved for patient recall for preventive procedures or review; requirements similar to those for analysis
Decision Support
Searches and Text Parsing
SNOMED CT facilitates searches for descriptions A simple keyword index may be generated from the descriptions and used for more effective searching although this may not be optimal due to:
Use of abbreviations
Word form variants
Word order variants
Word equivalences and combinations
Locally added mnemonics for frequently used descriptions
Composite coded meanings that can only be represented by:
Combinations of a code with one or more qualifying characteristics
Multiple codes related together by the patient record structure components
Searches with multiple redundant hits for a single code
When several synonyms of the same code match the search key
When techniques for word equivalences and combination are applied and return alternative descriptions related to the same code for two or more word equivalences
Searches with multiple redundant hits for a large number of closely related coded meanings
Search keys matching descriptions associated with a code with a more general meaning and many of its more specific hierarchical descendants
A further complication is the application of searches within subsets. This restricts the range of available concepts or codes; efficiency may depend on the relationships of keyword indices and subsets
Parsing or Encoding Free Text
The use of natural language parsing to encode free-text derived from typing, scanning, or voice recognition is increasing; the text of descriptions and associated search indices may assist with this process
Terminology Services
Terminology services should be implemented independent of application data; by individual applications or by terminology servers accessible by many applications
Advice
Application data cannot be specified to the same level of detail as terminology services. It us dependent on the general functionality of the application and its record structure
Providing advice early in the SNOMED CT implementation process is required. This helps with some issues that may not be immediately apparent to developers
Limited Applications
Code Recognition
It should be possible to distinguish a code from an earlier coding schemes (SNOMED, Read Codes, or NHS Clinical Terms) from the identifiers used in SNOMED CT
Equivalence
It must be possible to relate each code in early coding schemes (SNOMED, Read Codes, or NHS Clinical Terms) to a code in SNOMED CT
Query/Protocol Conversion
Patient Record Architectures
SNOMED CT is intended to represent clinical meanings in patient records
A patient record consists of a series of related statements that are organized under headings
The statements and headings may contain clinical codes derived from SNOMED CT
Headings, and other contextual elements, may modify the meaning of related statements
The relationship between a terminology, such as SNOMED CT, and a record architecture can be summarized as follows:
SNOMED CT codes and terms may populate different elements in the record structure
Different SNOMED CT codes may be applicable to different elements in the record
Some codes may not be appropriate for inclusion in the record
SNOMED CT should be evaluated within the context of evolving standards for patient record architectures. Recommendations based on the evaluations may include:
Possible changes to record architectures in order to realize benefits from SNOMED CT
Changes to SNOMED CT to better fit into record structures
Selecting SNOMED CT codes for use in specific record structure contexts
Expression Coordination and Equivalence
Some codes may be entered in a precoordinated or a post-coordinated manner. For example, "excision of ovary" might be entered by:
selecting the precoordinated code 83152002 |Oophorectomy (procedure)|, OR
alternatively by selecting the codes for
71388002 |Procedure (procedure)| and adding the qualifying characteristics: 260686004 |Method (attribute)| = 129304002 |Excision - action (qualifier value)| 405813007 |Procedure site - Direct (attribute)| = 15497006 |Ovarian structure (body structure)|
The coded meanings are stored in the forms entered. This may be using a single precoordinated code, a single post-coordinated expression, or a set of separate codes that together represent the clinical meaning.
A retrieval query must therefore search for the precoordinated and all possible post-coordinated ways of expressing equivalent meanings. This can be done using the Expression Constraint Language () and a terminology service that can compute subsumption between expressions.
These methods for retrieving records based on their clinical meaning rely on the formal definitions of SNOMED CT concepts being as complete as possible. Missing defining characteristics may result in problems with equivalence testing and therefore data retrieval.
Clinical Information
The ability to communicate clinical information (represented by SNOMED CT) between applications must be supported
Message specifications and other communication structures must accommodate SNOMED CT identifiers, and combinations of identifiers, in order to express postcoordinated coded meaning
Message Specifications
Current message specifications (e.g EDIFACT, HL7, and XML) use plain text files; SNOMED CT identifiers must use plain text so that they are appropriate for these messages
Postcoordinated Expressions
Classification
Based on recorded codes, mapping tables are used to generate statistical and administrative data
Automation of the process depends on the nature of the classification, the richness of the mapping table, and the functionality of the mapping software
Grouping
Mapping tables are used to generate groupings for funding, administration, etc.
Mapping to a classification, then using the classification codes to generate groupings, is an alternative method
Communication Specifications
Limited Applications
Applications vary in their ability to use terminological components.
Special consideration may be necessary for applications that require only limited use of SNOMED CT
Concepts in Different Languages
Translating SNOMED CT into other languages is required
Multiple translations may support communication of clinical information across language barriers
Patients
Allows coded meanings to be expressed at different levels of granularity
All changes to components are tracked and saved in history files (includes details about new components and changes to the status of components)
When a component is made inactive, relationships or references indicate the replacement or equivalent component
Includes mechanisms for representing subsets of codes and concepts for particular contexts in a record, decision support protocol, or data entry field
Includes formal definitions of codes represented by relationships with defining characteristics (e.g. the anatomical site of the code named appendicitis is the vermiform appendix )
Enables the consistent and reproducible storage of information, which is subsequently retrieved for decision support
Requirements are broadly similar to those for analysis
Decision support requires retrieval of selected records from an individual patient record
Requires real-time processing to determine code meaning equivalence
The advice provided should not place onerous requirements on applications with limited needs for the SNOMED CT terminology
It is inappropriate to have all-or-nothing requirements for SNOMED CT enabled applications
There must be support to convert queries and protocols, based early coding schemes (SNOMED, Read Codes, or NHS Clinical Terms), to SNOMED CT compatible forms
Communication of postcoordinated expressions may be possible using specific qualifier fields in messages. This can also be accomplished by using syntactic representation of identifier combinations; these must be consistent with message syntax and field size limitations
Codes are mapped to specific values, in an enumerated list, associated with a message or communication specification
Recognizing these mappings may prevent double data entry, when sending or receiving such messages
Patients may be users of SNOMED CT if they record information in their own medical records
This may require limited licensing of SNOMED CT for populations, in general
The meaning of a SNOMED CT code may be modified by its context within the record structure