OMG CTS II Vocab Requirements

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As part of the OMG Common Terminology Services (CTS) II RFP, there is an expectation that respondants will incorporate HL7 vocabulary requirements into their responses. The web link quoted in the RFP was not ideal for getting a good sense of HL7's vocabulary requirements and distinguishing them from other requirements. Therefore, this page has been constructed to provide a better overview and set of navigation of HL7's requirements.

HL7 has a metamodel for all HL7 artifacts that defines what artifacts can exist, what properties they may or must have, etc. This metamodel is expressed as a set of XML schemas which also defines a format for the persistence and exchange of HL7 artifacts. Every element, attribute, type, enumeration, etc. within the schemas includes documentation expressing the semantics and use of that element. Most elements also express a mapping to the UML metamodel. HL7's metamodel is referred to as the MIF (Model Interchange Format).

From a CTS II requirements perspective, only the meta model aspect is relevant. There is no expectation that CTS II functions will make use of MIF syntax. However, HL7 would have no objection if a respondent were to choose some portion (or even all of) the MIF syntax as part of their design if they found that desirable. A copy of the current draft of the MIF, constrained to only those parts relevant to vocabulary has been attached here. The 'root' schema for vocabulary is mif-model-vocabulary.xsd. You may find it helpful to browse the schema using a tool such as the schema view in Altova's XML Spy.

This section of HL7's wiki was developed to identify the underlying requirements that drove the creation of the HL7 metamodel. I.e. Why do we have the artifacts we do, why do they have the properties they do, etc. The focus of the wiki is the requirements, with cross-references made to the MIF elements that satisfy those requirements. It is these requirements that are expected to be satisfied by the CTS II solution.

The requirements are expressed as a hierarchy of inter-relating topics. In some cases, the solution chosen to solve one set of requirements has engendered an additional set of requirements. This process is reflected in the hierarchy of the requirements.

Some requirements are expressed in a generic form and apply to many or even all HL7 artifacts. However, from a CTS II perspective, only their applicability to vocabulary artifacts is relevant.

The hierarchy of pages documenting requirements relevant to vocabulary (in suggested reading order) is as follows:

Note: The MIF continues to evolve and the set of requirements documented here are still undergoing review by HL7. Therefore the contents of the wiki will likely be revised on occasion during the RFP process. Significant changes are not expected. However, respondents should monitor changes and consider them as part of their response. As much as possible, we'll try to summarize key changes on this page below: