1) CTS2 is a collection of standards for representing, exchanging, and querying terminological resources such as ontologies and coding systems. 2) It provides models, XML schemas, and rules for constructing URLs to access terminological content through RESTful web services. 3) CTS2 aims to address issues involving relationships between identifiers, namespaces, and service URLs when working with terminological content.

1. An Introduction to
Common Terminology
Services Release 2 (CTS2)
Harold Solbrig
Mayo Clinic

2. CTS2 Introduction
WHAT IS CTS2?

3. CTS 2
CTS2 is a cohesive collection of
standards for
representing, exchanging and
querying terminological
resources, built on the RESTful
Architectural Style.

4. CTS 2
CTS2 is a cohesive collection of
standards for
representing, exchanging and
querying terminological
resources, built on the RESTful
Architectural Style.

5. A “cohesive collection of
standards”
CTS2 is many small, interrelated
standards:
• Content
• Functional
• Representation

6. Content Standards
• Code System Catalog Entry – metadata about code
systems (aka. Ontologies, code sets, classification
systems, thesauri)
• Who publishes them, how often are they
released, what is their intended use, where do
you get them, what restrictions apply
• Code System Version Catalog Entry – metadata
about individual releases of code systems.
• When they were released, what formats are
available, where to get a copy, etc.

7. Content Standards
• Entity Description – the lexical (non-formal)
components of the actual contents of a version of a
code system. Entity description subtypes include
descriptions of classes, properties (aka.
Relationships, associations), and individuals.
• Association – the formal, logic-based descriptions of
entities.
• Structure: subject / predicate / target where
• Target :: entity reference, data or complex
expression

8. Content Standards
• Map Catalog Entry – metadata about a mapping
• Mapping – a set of assertions about the
relationship between the codes in a source code
system and one or more targets
• Metadata – who publishes it, what code systems
it maps, etc.
• Map Version – the contents of a mapping at a given
point in time.
• Can represent 1  1, 1 n, m n mappings
• Includes ability to represent complex rules
• Map targets can be complex structures

9. Content Standards
• Value Set Catalog Entry – metadata about a value
set
• Value set – a collection of codes (represented as
URI’s in CTS2) drawn from one or more code
systems
• Metadata – who created it, what it is for, what
code systems it includes, where to get it
• Value Set Definition – a set of rules for constructing
a value set. Can be “intensional” or “extensional”
• Resolved Value Set – the result of applying a
particular version of a definition against particular
versions of code systems. Note: First class entity in
CTS2.

10. Content Standards
• Concept Domain Catalog Entry – metadata about a
concept domain
• Concept domain – a field, column, element, etc.
(aka Data Element Concept in ISO 11179)
• Metadata – who created it, what it is for, etc.
• Concept Domain Binding – the association of a
concept domain and a value set in a contextual
setting
• Aka Data Element in ISO 11179

11. Functional Axis
• Read – how to retrieve resources by ID
• URL Construction – HTTP Rest
• Method Invocation – SOAP / POJO /
Python, etc
• Query – how to retrieve resources by
content
• Import / Export – how to load and/or
retrieve content in external formats

12. Functional Axis
• Update – how to exchange and synchronize
content
• Complete images
• Incremental changes
• Maintenance – API for building an update
• History – access to what changed when for a
given resource
• Temporal – how would/will the service
behave at a past (or future) date

13. Representational Axis
• XML - CTS2 includes XML Schemas for each
of the resources described above
• JSON – (non-official) JSON rendering
• Goal is to produce official at subsequent
date
• RDF – “cannonical” RDF representation of
CTS2 content
• Not included in first release

14. CTS 2
CTS2 is a cohesive collection of
standards for
representing, exchanging and
querying terminological
resources, built on the RESTful
Architectural Style.

15. What is CTS2?
A collection of:
1) Models – formal descriptions of what
things are and how they are invoked
2) XML Schemas – “sensible, (reasonably)
accessible descriptions of the various
resources
3) Rules for constructing URL’s (or
methods for SOAP/Object environment)
to access this content.

16. What is CTS2?
Additional value added:
1) Addresses the relationship between
URI’s, OID’s, namespaces and service URLs
2) Addresses issues involving “bnodes” and
“compositional structures”
3) Sits on the Ontology / Terminology boundary
4) Incorporates components of
OMV, BioPortal, SKOS, DC, OWL, SNOMED-
CT, and many others…

17. Key Points
CTS2 is an interface standard – it is
not software.
CTS2 is a standard for terminology
access – it is intended to be
extendable and configurable
CTS2 is a modular – no gain, no pain
(aka. Linear Value Proposition)

18. Evolution
Common Terminology Services - Release 2
Evolved from:
• OMG LQS Specification (1999)
• OO Model, read only, but laid most of
the groundwork
• HL7 CTS Specification (2004)
• ANSI and ISO Standard
• SOA Model, read only, reduced scope
from LQS
11/2011 © Copyright 2011, Mayo Clinic 18

19. CTS2 Introduction
PROCESS

20. Healthcare Service
Specification Project
Developed through the Healthcare
Services Specification Project (HSSP) - a
collaboration between Health Level 7
(HL7) and the Object Management Group
• HL7 provides the requirements as a
Service Functional Model
• OMG develops the formal specification
• HL7 adopts and validates via an HL7
Implementation Guide
11/2011 © Copyright 2011, Mayo Clinic 20

21. Healthcare Services Specification
Project (HSSP) Workflow
HL7 OMG Vendor
1 Community
SFM
2
SFM
RFP
Proposed
3 Standard
Beta
4
Standard
4
FTF
HL7
Implementation
Final Corrections /
Guide
Standard 5 Clarifications
11/2011 © Copyright 2011, Mayo Clinic 21

22. Healthcare Services Specification
Project (HSSP) Workflow
HL7 OMG Vendor
1 Community
SFM
SFM 2 We Are
RFP
Here…
Proposed
3 Standard
Beta
4
Standard
4
FTF
HL7
Implementation
Final Corrections /
Guide
Standard 5 Clarifications
11/2011 © Copyright 2011, Mayo Clinic 22

23. OMG CTS2 Specification
Other Key Points
• Generic – NOT healthcare specific
• Supports Semantic Web – RDF and OWL2
• Not intended to be constraining
• Extensions are ok – in fact
encouraged!
• Purpose is not to say what can be
done, but rather to say how common
things can be done consistently
11/2011 © Copyright 2011, Mayo Clinic 23

24. CTS2 Scope
SNOMED- Gene
CT Ontology
ICD-10
HL7
11/2011 © Copyright 2011, Mayo Clinic 24

25. CTS2 Scope
SNOMED- Gene
CT Ontology
ICD-10
HL7
11/2011 © Copyright 2011, Mayo Clinic 25

26. CTS2 Scope
SNOMED- Gene
CT Ontology
ICD-10
HL7
11/2011 © Copyright 2011, Mayo Clinic 26

27. CTS2 Scope
SNOMED- Gene
CT Ontology
Generality means
ICD-10 that some things
aren’t covered
HL7
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