The use of this reference set structure is now discouraged as it requires implementers to create a new refset concept for every new annotation type.   A new refset format is currently being discussed here: SNOMED CT Annotations and alternate RF2 specifications will be generated in due course.


An 900000000000516008 | Annotation type reference set| allows String to be associated with components for any specified purpose.

Data structure

An annotation reference set is a String reference set used to apply text annotation to selected SNOMED CT components.

Table Annotation 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.

In this case, a subtype descendant of: 900000000000516008 | Annotation type|


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

The component to which the annotation is being applied.




The text annotation to attach to the component identified by referencedComponentId .



The following metadata in supports this reference set :

Table Annotation References 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 tables below show the descriptors that define the structure of the 900000000000516008 | Annotation type reference set| pattern and examples of the descriptors for specific reference sets that follow this pattern.

Table Descriptor Template for Annotation Reference Sets

The attributeType for the Annotation field can be any descendant of the " string " concept in the metadata hierarchy. This hierarchy is described in more detail under the " Reference set descriptor" section.

Table Descriptor for the Associated Image Annotation Reference set

Note that in the table above, the 900000000000469006 | URL| concept is a descendant of | string | concept in the metadata.

Annotation Reference Set Example

As no annotation reference sets are included in the International Release, these sample rows are for illustration only.

Table Example of Associated image Annotation Reference Set




In the above example, the two URLs have been used to annotate two SNOMED CT concepts with images on the web. It is not recommended that this mechanism be used to annotate concepts with text that may require translation to other languages. Instead, such text should be included under an appropriate description type within the Description.