This section outlines the rationale for distributing an OWL representation of the 

Gloss
t stated view

 of 

Gloss
t concept definitions

 and provides an overview of the way OWL axioms are represented in 

Gloss
t SNOMED CT release files

.  More detailed information is published separately in the  DOCOWL and the  DOCLPS.

Rationale for Using OWL

The mismatch between the requirements for representing enhanced 

Gloss
t concept definitions

 and the capabilities of the current 

Specref
RefType file t stated relationship file

 might in theory be addressed by addition of columns to the file or adding additional information in reference sets. However, in practice this would create a more complex solution able to support a specific set of enhanced features.

Adopting the well-established OWL standards formats offers a more flexible solution that can represent the full range of 

Gloss
t description logic

 features. This approach enables 

Gloss
t SNOMED Internation

 to specify a particular logic profile to be applied to current releases of 

Gloss
t SNOMED CT

, with the option to extend that profile in the future. Future revisions of the logic profile would not require a change in the distribution file structure provided these were supported by an OWL syntax.

OWL Axioms

OWL axioms can be represented using several different syntaxes. SNOMED International has chose the

Gloss
t OWL Functional Syntax

 as its standard representation.

Glossary include
Gloss OWL Functional Syntax Suffix is Def inline Prefix The Link true

OWL Expression Axiom Set

OWL axioms are distributed in a 

Specref
t reference set

 that follows the  OWL Expression Reference Set specification. The axiom itself is contained in a string field and the 

Gloss
t concept

 whose definition it contributes to is referenced by the the 

Specref
t referencedComponentId

. Although a single row in the reference set can provide a 

Gloss
t sufficient definition

, the definition of a single concept can also include several axioms each represented by a row in the reference set.

Comparing Stated Relationships and OWL Axioms

Caption label
CapId appendectomy-diagram CapType Figure
Diagrammatic representation of the definition of appendectomy

Caption reference
CapRefId appendectomy-diagram CapRefType Figure

 shows the diagrammatic representation of the 

Gloss
t stated view

 of the definition of 

Concept
t 80146002 |Appendectomy|

. 

Caption reference
CapRefId appendectomy-stated-rels CapRefType Table

 shows the same definition as represented by three rows in the 

Specref
RefType file t stated relationship file

 together with the 

Specref
t definitionStatusId

 in the 

Specref
RefType file t concept file

.

Caption label
CapId appendectomy-stated-rels CapType Table
Stated relationships and definition status for the concept appendectomy

Caption reference
CapRefId appendectomy-owl-axiom CapRefType Table

 shows a row in the 

Specref
t OWL axiom reference set file

 representing the same definition. As shown by this example, a single 

Gloss
t sufficient definition

is represented by a single row in the reference set. However, some 

Gloss
t concept definitions

 may require multiple rows in the reference set. Situations in which multiple row are required include:

• Concepts with multiple 

  Gloss
  t sufficient definitions

  , each of which requires a separate row in the reference set. 
• Concepts with additional 

  Gloss
  t necessary conditions

   that are not part of a

  Gloss
  t sufficient definition

  , each of which requires a separate row in the reference set.

Caption label
CapId appendectomy-owl-axiom CapType Table
Example of OWL axiom refset representation of the definition of appendectomy