A | Simple type reference set| allows a set of components to be specified for inclusion or exclusion for a specified purpose. This type of reference set represents an extensional definition of a subset of SNOMED CT components. Thus it can be used to fully enumerate a subset of concepts, descriptions or relationships.

See also Query specification reference set, which can be used to represent an intensional definition of a subset of SNOMED CT components. In an intensional definition, the members of the subset are specified by rules rather than by enumerations (e.g. all subtypes of a specified concepts).

Reference Set Data Structure

A Simple reference set does not have any additional fields.

Table Simple Reference Set - Data Structure


Data type


Part of Primary Key


A 128 bit unsigned Integer, uniquely identifying this reference set member.

Different versions of a reference set member share the same id but have different effectiveTime. This allows a reference set member to be modified or made inactive (i.e. removed from the active set) at a specified time.

NOYES (Full /Snapshot)

The inclusive date or time at which this version of the identified reference set member became the current version.

Note: In distribution files the effectiveTime should follow the short ISO date format (YYYYMMDD) and should not include the hours, minutes, seconds or timezone indicator.

The current version of this reference set member at time T is the version with the most recent effectiveTime prior to or equal to time T .


YES (Full)

Optional (Snapshot) 

The state of the identified reference set member as at the specified effectiveTime .

If active = 1 (true) the reference set member is part of the current version of the set, if active = 0 (false) the reference set member is not part of the current version of the set.


Identifies the SNOMED CT module that contains this reference set member as at the specified effectiveTime .

The value must be a subtype of 900000000000443000 | Module (core metadata concept)| within the metadata hierarchy.


Identifies the reference set to which this reference set member belongs.


A reference to the SNOMED CT component to be included in the reference set.



Simple References Sets are subtypes of 446609009 | Simple type reference set| in the metadata hierarchy.

Figure Simple Reference Sets in the Metadata Hierarchy

Reference Set Descriptor and Example Data

Notes on the tables used to show descriptors and examples

The reference set example tables on this page have been revised as follows to aid clarity and understanding:

  • The first four columns which are present in all release files are not shown. The omitted columns (ideffectiveTimeactivemoduleId) are used in the same way in all referenced sets to support identification, versioning and packaging. They do not directly affect the specific features of a particular reference set or reference set type.
  • Reference set columns that contain SNOMED CT identifiers are expanded to show details of the concept or description referenced by that identifier. In some cases, the term is shown in the same column using the expression syntax, in other cases an additional column with a name suffix '_term' has been added. In the standard reference set files only the identifier is present in the column and there is no added column for the term. When using reference sets, the term and other details of the component are looked up from the relevant component release files.

Descriptor Template

The table below shows the descriptor for a specific reference sets that follows the 446609009 | Simple type reference set| pattern.

Table Refset Descriptor rows for the Simple Reference Set Type


referencedComponentId (Referenced component)

attributeDescription (Attribute description)

attributeType (Attribute type)

attributeOrder (Attribute order)

900000000000456007 | Reference set descriptor|

447566000 | Virtual medicinal product simple reference set|

449608002 | Referenced component|

900000000000461009 | Concept type component|


Example Data

Table Example Data for a Simple Reference Set