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Value Set Definition Standard Project

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A New Normative Standard for Value Set Definitions


FINAL REVIEW OF STANDARD in preparation of PUBLICATION to occur at 2016 May WGM MONDAY Q1

[From the PSS] Describe the elements that make up a “Value Set Definition”, and ballot this as a normative HL7 specification, including a demonstration of how this is met in FHIR profiles and HL7 Model Interchange Format (MIF).

The definition of value sets is a required activity in completing the specification of most health information technology artefacts. To date, the approach for doing so has not been consistent within HL7 constructs and elsewhere. Many of the required elements and approaches are embedded in existing HL7 artefacts but not consistently. Currently, an explicit list of all the fields in an HL7 value set definition are surfaced only in the informative balloted MIF, with a general description of them in the normative Core Principles specification. A more accessible and standardized list of these fields is required to facilitate interoperability and sharing of value set definitions across HL7 artefacts and the Health IT community at large.

Success criteria: Publishing of the normative standard, and a demonstration of value set definitions that conform to this published normative specification.

Project Processes

This project is using DropBox as a collaborative document sharing process during the formative draft development process. If you are interested in viewing the current draft please attend the meetings. If you are interested in participating in the editing and review of the drafts, please send a request to get access to the dropbox folder to Rob McClure ( rmcclure AT ).

Project Participants

Preparation Tooling

Conference Call Schedule and Minutes

Remember USA is now on STANDARD TIME EST is UTC -5
Standard meetings are - Tuesdays @ 4pm EST for 90 min.

Telephone uses standard HL7 Vocab number: 1 (770) 657-9270,,,598745#

Meeting will be one of the following web share environments

Mikogo session

If the above link does not work, you can follow these steps instead to join a session:
# Go to
# Enter the Session ID: 073-003-565
# Enter your name
# Click "Join Session"

Join.Me session

Current Weekly Agenda

  1. Agenda:
    1. Discuss use of VSD in Templates
    2. Review of final "needs discussion" item(s) in ballot
    3. Think of examples
    4. Work on glossary

Note - fixed CodeBasedContentSet on 2015-08-21 based on RM and TK skype call. Also added expressions as allowed "code". Need to consider where to place something that would allow expressions as valid members of a value set. Some sort of flag. This is also something that belongs on the binding syntax. Both places likely needed. As a VSD element it would control if the TS should consider an expression as valid - IE< this is a receiver function, and not so much a definition element that requires all potential expressions to be enumerated as "standing members" for any expansion.

Updated Current Documents

Updated as of 2016-04-05

  1. Current VSD Spec doc HERE
  2. Current Ballot Comment doc HERE

Value Set Definition Examples

Examples based on the HL7 Expression Syntax described in the VSD standard are available for download HERE.

Running list of Completed Issues

  1. Will submit as DSTU in Normative track and not as Normative in first ballot. [2014-07-22]
  2. We completed the review of the Logical Elements/Functions to define Content Logical Definition based on the MIF
    1. See Valueset MIF ContentDefinition for updated comments.
  3. Discussion on how to control use of DYNAMIC defined value sets continued on 12/20 meeting.
    1. Rob and Lloyd still have to create document and use cases to explain approach to "STATUS" / DYNAMIC stability.
  4. Metadata sheet review now complete
    1. Completed discussion of Value Set Expansion metadata with changes added to end of spreadsheet.
      1. A Value Set Definition can reference 0..* "Trusted Value Set Expansion Reference" that can be a service or an actual expansion
      2. An Expansion can be characterized by a date (required), a time (optional) and an identifier (optional)
  5. As of VSDSpec v18, UML model accurately describes those elements that are "definitional" in that if they change, a new value set or value set version should be created.
  6. 4/22/14 Completed documentation of determination of VSD version STATUSes
  7. This initial ballot will leave inclusion of concept expressions as value set members as OUT OF SCOPE. This remains highly important but will be addressed in the following ballot.
  8. This document has the abstracted decisions from minutes. [1]
  9. We will allow the use of slightly more complex datatypes (DSET and EN are currently used) [Example content attribute was discussed when this decision was reached]
  10. Purpose changed to Scope in v24
  11. We allow NonComputableContent CE to be included in a general CLD, therefore some CLD may have both computable and non-computable content.
  12. Clarified that Value Set Reference CE should not also allow Code System Constraint Parameters as such a thing could be inconsistent with the actual referenced value set.
  13. Clarified that the CLD “slot” in the value set version actually should hold, in essence, a “UnionwithContent” operation on the included content expressions. This can either be an implicit description of how to manage the CEs listed, or we can explicitly have a CLD point to 1..1 UnionWithContent
  14. NCC will remain as part of the MIF-based syntax as a type of Code System Content with LOTS of best practice guidance by Lloyd and Ted. This DOES MEAN that MIF-based syntax CLD is not always computable 2015-06-09

  1. Items for discussion at upcoming Work Group Meeting
    1. Acceptable modeling approach to add additional syntax types for CLD (see meeting notes Sept 23rd).
    2. discussion of Jay Lyle's alternative model approach - he is to identify elements that he has left out and/or added before the WG meeting. Discussion Tuesday Q4.

Final version of the Ballot - here.

Minutes documents:

All Minutes are on the VSD Minutes Page

Key Target Dates

Review of final publication draft at 2016 May WGM.
Publication right after 2016 May WGM.
No need for re-ballot given DSTU status unless we want to do so.

Project Documents

The project working documents are being maintained using Google Docs. These can be found at: Links to project documents