HL7 Common Terminology Services (HL7 CTS) provides a common standard interface to terminology servers/services. This insulates other systems that access terminology services from knowing the internal structure of the terminology service. The client applications can access a terminology service without knowing its internal database structure or data model. It also allows the terminology service provider to make internal changes to the terminology without breaking the applications that query the terminology service.
HL7 CTS allows the terminology service and the client EMR or messaging applications to be truly independent of one another, and one of these can be modified or replaced without impacting the others. HL7 CTS allows true plug-and-play interoperability between the terminology service and other appllications.
HL7 CTS v1.2
The current released version of the HL7 CTS standard is version 1.2. HL7 CTS v1.x allows read-only capabilities -- it allows one to query a terminology service, but does not support authoring capabilities. HL7 CTS v1.2 only supports one version (often the latest version) of a given terminology. It does not support multiple concurrent versions of a given terminology.
The 3M Healthcare Data Dictionary (3M HDD) provides a CTS v1.2 inteface implemented as a web service.
You can download the HL7 CTS v1.2 specifications from the following links hosted by Mayo Clinic*:
CTS Specification version 1.2 [Final Draft] - November 2004 - (HTML) (XML) (ZIP file of everything)
IDL for specification
* Reference: Mayo Clinic CTS v1.2 website.
HL7 CTS2
HL7 Common Terminology Services version 2 is the upcoming version of the CTS standard. 3M is a co-author of HL7 CTS2. HL7 CTS2 is part of the Healthcare Standards Specification Project (HSSP), a collaboration between HL7 and OMG. As part of this project, HL7 will define the functional model, and OMG will define the platform independent and platform specific models of CTS2.
HL7 CTS2 will support both read (querying) and write (authoring) capabilities. It also supports federated (distributed) terminology authoring and online/automated terminology (or subset or valueset) distribution. HL7 CTS2 also supports multiple concurrent versions of a given terminology.
HL7 CTS2 has passed the HL7 ballot as a draft standard for trial use (DSTU). OMG will now continue with the development of the platform independent and platform specific models. 3M will do a pilot implementation of the CTS2 beta specification after it is published by OMG, and will update it to comply with the final specification after it is released by the OMG as well.
Reference: Mayo Clinic CTS2 website.
