Data Standards

TypeOverarching Standard
Effective Date 


Defines detailed technical standards for the storage, management and organisation of data and specifies standardised reference data, terminology and codes.

Data Standards is a mandatory technical standard which defines the data and information standards that must be adhered to and the operational and information reference data such as clinical terminology, drug database data sets, and organisational codes which must be utilised within the Solution to provide consistency of information.

NHS data standards are contained in the NHS Data Dictionary and Manual in the form of an entity relationship diagram or data model. The NHS Data Dictionary and Manual also holds the standards for field lengths and formats, and codes for classification lists.

Solutions are to use Organisation Data Service (ODS) data as the primary source of reference data for NHS related organisations and individuals. Solution will provide the UK Edition of SNOMED CT as its primary coding scheme; this will have, where appropriate, primacy over any other deprecated coding terminology For further information, see SNOMED CT.

Solutions are expected to enable efficient coding, and retrieval of clinical information for use both within the Catalogue Solution and other Solutions externally by appropriate third parties to support on-going and future Patient care. Clinical Terminology, such as SNOMED CT, is essential for the interoperability of electronic health records across care settings. The standard supports the conversion of machine-readable code into meaningful, human-readable defined text and vice versa, thus providing a basis for supporting communication between clinicians, and the safe transfer of data between Solutions.


Data & Information Standards

Requirement IDRequirement TextLevel

NHS Data Dictionary standards

Adhere to NHS Data Dictionary and Manual standards for field lengths and formats, and codes for lists.


NHS Number ISB

The supplier will adhere to the NHS Number Standard (ISB 0149)


Reference Data

Requirement IDRequirement TextLevel


The supplier will ensure that where (International Classification of Diseases) ICD encoding is required, it shall adhere to the ICD 10 specification.

For further information on classifications see Terminology and Classifications and TRUD.



The supplier will ensure that where OPCS encoding is required, the Solution adheres to the latest version, currently OPCS-4.8 specification. 

For Standard on OPCS, see SCCI 0084 - OPCS Classification of Interventions and Procedures

For further information on classifications see Terminology and Classifications


Coding & Terminology - Up to date edition

The most up to date UK Edition of SNOMED CT will be implemented within the Solution.

See TRUD for the latest edition.


Coding & Terminology - Single active edition

The Solution will not allow more than one edition of the primary coding scheme to be active at any one time and the Solution will only allow the use of the latest installed edition of this coding scheme.


Coding & Terminology - Same edition of terminology

Where a Solution uses more than one terminology product (e.g. subsets, mapping tables), all products will be based on the same Edition of that terminology.


Coding & Terminology - ISB0034

SNOMED CT covers clinical terms for use by Secondary, Primary, Health and Social care. The Supplier will ensure that where SNOMED CT or any of its derivative products are used, Solutions will implement and use the SNOMED CT Standard as defined by SNOMED International. SNOMED CT (SCCI 0034) and the NHS Digital Terminology Service.

For further information, see SNOMED CT


Coding & Terminology - Excluded concepts

When using SNOMED CT the Solution will not present for entry into the Patient Record any of the following concepts or their children:

  • 410663007 | Concept history attribute (attribute) |
  • 408739003 | Unapproved attribute (attribute) |
  • 900000000000441003 | SNOMED CT Model Component (metadata) |



SNOMED CT descriptions

Support all SNOMED CT published variations/types of clinical term within a Concept, including Fully Specified Name, Preferred Term, and Synonyms.

When supporting data entry and viewing data:

  • Where a User is searching for a term, all synonyms to be displayed
  • Where a User has ‘found’ or selected a term, the Preferred Term to be offered/highlighted to the User
  • Where a User wishes to enter a term other than the Preferred Term, this will be permitted
  • The selected clinical term will always be displayed irrespective of method to select a term e.g. if a User searched for Term A and found and selected a Preferred Term i.e. Term B, Term B to be stored in the Patient Record
  • All SNOMED CT concepts (excluding Metadata concepts) can be available to view (if not select), even when a managed subset of SNOMED CT is being used by the Solution to maintain visibility of relationships and hierarchical context.

The Solution to use the Realm Description Refset (available in the language folder of the release files on TRUD) for UK Preferred Terms



Local collections of clinical terms

Define and manage local collections/lists of clinical terms (known in SNOMED CT as subsets). Functionality to include:

  • Unique identifier and/or name and version for each collection/list
  • Addition of multiple clinical terms – User to be notified / alerted if they attempt to add a clinical term to collection where another clinical term that represents the same Concept already exists within the collection/lists, though the Solution won't restrict subsequent inclusion of the term within the collection/list


Sharing collections of clinical terms

Support the sharing of collection/lists of clinical terms with other Users. 

  • Between organisations
  • Export collection/lists i.e. SNOMED CT subsets for import and/or replication within other Solutions (only applicable for Solutions using SNOMED CT as their primary source of coding scheme)
  • Import collection/lists i.e. SNOMED CT subsets received from other Solutions, professional bodies and NHS Digital Terminology Service

Amendment of unique identifier and/or name and version will be allowed during this sharing to prevent conflicts with collections/lists in other Solutions



Temporary/local terms

Define, use and manage temporary/local terms i.e. non-national codes that are expected to be superseded, whether these are local to an organisation or not e.g. for specific local purposes or as a ‘placeholder’ while a new clinical term is being requested/added to the coding scheme by the relevant authorities. Functionality to include:

  • Clear differentiation between temporary/local terms and clinical terms from SNOMED CT
  • Replacement of such temporary/local terms across the Solution e.g. upon release of appropriate national code
  • Indicate to Users each time they opt to use a temporary/local term that the term will not be recognised outside of the organisation/Solution
  • Removal of temporary/local term to prevent further usage i.e. make such a term inactive

Solutions that provide for codes local to the organisation, will utilise the SNOMED CT namespace feature; registering a namespace to their organisation. All messages will use the organisation namespace identifier for local codes and not the national SNOMED identifier so as to distinguish between national and local codes.

All management of temporary/local terms will be conducted in a safe way that enables any records to be retrieved that might have been stored using a temporary/local term



Search for and select clinical term(s)

Search for and select any clinical term from the full list or defined in GP-03.2-03 to support data entry, in each of the following ways:

  • Predictive text/term suggestion feature (possible applicable terms based on entry of full or partial term, description or code), with the ability for a User to select not to encounter this functionality in their use of the Solution
    • Data entry search for clinical terms to be case independent and the full clinical term description to always be displayed irrespective of whether the User enters:

      • full / part code or description
      • upper or lower case
  • Display all concepts where the synonym matches the search
  • Selecting a term from a full list or subset of terms e.g. scrolling through a dropdown list
  • Finding a term from a hierarchical and/or structured folder display i.e. ‘drill down’ levels of detail to find the appropriate term. User to have ability to view all levels of granularity and to select any level of parent, or Child term


View/display clinical term(s)


  • The clinical term description (this can be followed by the code as appropriate for the coding scheme being used)
  • All clinical terms as they were recorded in the Patient Record, including where a term:
    • has subsequently become inactive
    • is not used/selectable within the Solution i.e. display terms outside of organisation’s subsets or coding schemes
  • Upon User demand:
    • the associated information of the clinical term (e.g. type of term such as finding or procedure)
    • the entire clinical term (Fully Specified Name and code)


No longer 'active' clinical terms

Support ongoing view/retrieval of terms no longer considered ‘active’ within the current UK Edition of SNOMED CT and utilise the Query table provided by the Terminology Service to manage the retrieval of inactive concepts.

 User to only enter active clinical terms – i.e. can be prevented from data entry of inactive clinical terms into a Patient’s Record


Support deprecated coding schemes

Support ongoing view/retrieval of terms previously captured in any previously supported deprecated coding schemes such as Read v2 or CTV3


Preserve previously coded data

All previously coded data currently stored within the Solution in either Read v2 or CTV3 will always be preserved within the record



Data Archetypes - Drug Allergy

Support the Drug Allergy Data Archetype as per:



Terminology Mapping

Where a Solution contains legacy primary clinical coded data (either Read v2 or CTV3) the Solution to map to SNOMED CT using the Mapping Tables published on TRUD; the maps to be used irrespective of the isAssured flag (indicator within the mapping tables). Suppliers are required to do this once when migrating from legacy coded data to SNOMED CT but will continue to be able use the mapping tables if they so choose.

The Solution to allow users to identify coded data mapped using an unassured map.

For all other purposes, the IsAssured flag to be considered/interpreted and used as specified by the relevant requirements e.g. GP2GP. Where not specified the map to be used irrespective of the flag status.

Suppliers can use alternative maps as agreed with NHS Digital for the codes highlighted for special attention (e.g. for codes with values using the 'Alternate Maps' file) - see NHS Data Migration on TRUD.


Amendments to NHS Digital Mapping Tables

Where a Solution contains legacy primary clinical coded data (either Read v2, or CTV3) to address errors or agreed changes to maps in the national mapping tables, the Solution to ensure it is possible to re-map data already mapped to SNOMED CT via an updated mapping table.


Coded Data Preservation and Storage

For new data in SNOMED CT, the Solution to be able to provide the Description ID, Description Text, and the Concept ID.


Coded Data Export/Extraction

Where a Solution contains data stored as Read v2 or CTV3 this to be retrievable (on screen or via any other activity), but expressed in SNOMED CT.

Where a mapping has taken place, the Solution to also be capable of exporting/extracting the original Read v2 or CTV3 coded data (including code, term and description) i.e. export/extract both the SNOMED CT data and the source data from which the SNOMED CT data was derived/mapped.


Code Mapping/Migration Audit Trail

The Solution to retain in full, an audit of all past and present code mappings/data migration activity, and for this to be accessible with the correct permissions via the Solution User Interface.

See Information Governance Standard for audit requirements


SNOMED CT Searches

Systems to consider the clinical safety implications in relation to inactive content returned in searches. The UK Query table is recommended for consideration as the approach for accessing inactive SNOMED CT content.

Further information on the clinical safety issues is provided in this factsheet.

The UK Query Table is available via TRUD and is accompanied with technical documentation.


Data entry of Inactive SNOMED CT Content

A SNOMED CT description can be made inactive while the concept remains active. Where this occurs, suppliers to prevent the SNOMED CT descriptions from becoming available for data entry.

A SNOMED CT concept can be made inactive, while its descriptions remain active. Where this occurs, suppliers to prevent the descriptions and thus the concept being available for data entry.

For existing templates and other data entry artefacts:

  • Supplier developed templates and data entry artefacts to be updated to remove inactive content within contractual timeframes or within six months of the content becoming inactive whichever is sooner.
  • User developed templates and data entry artefacts should be updated to remove inactive content within contractual timeframes or within six months whichever is sooner. The system must make it clear to users which artefacts require attention.

Coding & Terminology - Other clinical coding schemes

Solutions will also support the use of other clinical coding schemes specifically required by the Authority in support of message exchange between Solutions.

See TRUD for mapping between coding schemes


Coded data import and receipt

System to support the receipt of coded data in SNOMED CT from external systems e.g. via a secondary care discharge summary/letter.



Primary Source of organisations and individuals reference data

Use ODS as the primary source of reference data for organisations and individuals (ODS is the legal source for organisational information).

For further information see ODS.

Also see TRUD link for ODS


Health and Social Care Organisation Reference Data - New identifier structure

Adhere to the aspects of DCB0090 regarding the structure and format of organisation codes.

For further information see latest version of DCB0090: Health and Social Care Organisation Reference Data


Health and Social Care Organisation Reference Data - XML release format

Adhere to the elements of DCB0090 regarding the move to xml release format, the release mechanism and APIs.

For further information see latest version of DCB0090: Health and Social Care Organisation Reference Data


NHS Dictionary of Medicines and Devices (dm+d)

The Supplier will ensure that all Solutions support the NHS Dictionary of Medicines and Devices (dm+d) Standard.

dm+d is a dictionary containing unique identifiers (codes) and associated textual descriptions for representing medicines and medical devices in information systems and electronic communications. This is of particular importance to the supporting of prescribing items. See Dictionary of medicines and devices (dm+d)


Automatic identification and data capture (AIDC)

The supplier will ensure that where Automatic identification and data capture (AIDC) is used that the ISB Standards are followed.

For Standards on identification see: 

ISB 1077 - AIDC for Patient Identification

ISB 0108 - AIDC: Automatic Identification and Data Capture



Maintain/store original unit of measure

Maintain/store original unit of measure whether input by a User in the Solution or received electronically



Numeric conversions/comparisons (units of measure)

Ensure all/any numeric data displayed for comparative purposes e.g. graphs or tables of data, use the same unit of measure

  • It will be made clear to the User if a conversion has taken place, and to what items
  • The original value and unit will be easily accessible by the User where a conversion has taken place

The Solution supplier will obtain agreement from NHS Digital for any conversion processes used and any algorithms used for such a conversion to be displayed to the User.



Prevent amendment of reference data

Prevent  Users from amending the source/underlying data from any nationally provided Reference Data



Reference Data (Version History)

Suppliers to have the ability to identify what version of reference data was in use at any point in time.



Subscription to Notification Services

The Supplier will subscribe to the following TRUD services:

  • UK Edition of SNOMED CT  – Release Format 2 (RF2)
  • NHS Data Migration
  • UK SNOMED CT Query Table and History Substitution Table
  • NHS Dictionary of Medicines and Devices (dm+d)
  • Organisation Data (ODS)

Subscription to these services will ensure that the supplier is notified (via email) on the day that any new release is made available to download from TRUD. The notification date will be regarded as the date of release.


Reference Data Updates

The Supplier will deploy updates to any reference data within 8 weeks of its release.

Release notifications are issued by TRUD.



Applicable Capabilities

All suppliers Solutions delivering any Capabilities will need to meet this Standard.


Items on the Roadmap which impact or relate to this Standard

Suppliers will not be assessed or assured on these Roadmap Items as part of Onboarding