Value Set Versioning

Value set versioning - The model in section 5.3 needs to include versioning for value sets, and a version parameter is needed in several functions (e.g. isCodeInValueSet). This is particularly true because there isn't a single release for all V3 messages - some will pass membership ballot, value sets will change, and then other specifications based on the value set will pass membership ballot. If committees have declared CNE value sets, these are fixed at the time the ballot passes.

Use Case Name: Value Set Versioning

• Description: A Value Set is a constraint mechanism for a collection of valid coded values from a code sysem(s). CTS2 needs to be able to represent multiple versions of a value set. The interface needs to support:

1. 1. Enumeration of the versions of value sets supported by the interface
   2. The ability to query version history of a value set - when it was introduced, when it was changed, when it was withdrawn, what happened to it, etc.
   3. The ability to select a specific version of a value set and make queries relative to that version

• Who needs it and why? Terminology services may need to support the management of value sets within both applications and messages. It is common for codes to be sourced from specific value sets or terminology subsets, rather than from the parent terminology eg. the acceptable codes in a problem field of an EHR may be drawn from the Disease hierarchy of the terminology. Value sets are defined by application or message owners and may draw their content from a specific version of a terminology or coding system. Valuesets are synonymous with a terminology subset. This can be done by selecting specific concepts or a concept and its children.

1. HL7 has determined that value sets should be registered and allocated an OID. Value sets will change over time and hence will also require version codes.
2. Custodians or editors of valuesets will require a capacity to be altered to logical changes in the value set which occur as the result of new versions being created of the value set's parent codeset.

• Why should this be standardized? - This functions function is required to support terminology subset/valueset management.

• Questions and issues:
  • Are value set versions linked to Code System versions?