This section outlines the rationale for distributing an OWL representation of the 
of 
and provides an overview of the way OWL axioms are represented in 
. More detailed information is published separately in the SNOMED CT OWL Guide and the SNOMED CT Logic Profile Specification.
Rationale for Using OWL
The mismatch between the requirements for representing enhanced and the capabilities of the current 
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 
features. This approach enables 
to specify a particular logic profile to be applied to current releases of 
, 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 
as its standard representation.
OWL Expression Axiom Set
OWL axioms are distributed in a 
that follows the OWL Expression Reference Set specification. The axiom itself is contained in a string field and the 
whose definition it contributes to is referenced by the the 
. Although a single row in the reference set can provide a 
, 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
Diagrammatic representation of the definition of appendectomy |
shows the diagrammatic representation of the of the definition of 
. 
shows the same definition as represented by three rows in the together with the 
in the 
.
Stated relationships and definition status for the concept appendectomy |
id | effectiveTime | active | .. | definitionStatusId |
| 20020131 | 1 | .. | |
id | effective Time | active | .. | sourceId | destinationId | relationship Group | typeId | .. | .. |
.. | 20180731 | 1 | .. | | | 0 | | .. | .. |
.. | 20080731 | 1 | .. | | | 1 | | .. | .. |
.. | 20080731 | 1 | .. | | | 1 | | .. | .. |
shows a row in the 
representing the same definition. As shown by this example, a single is represented by a single row in the reference set. However, some may require multiple rows in the reference set. Situations in which multiple row are required include:
- Concepts with multiple
, each of which requires a separate row in the reference set.
- Concepts with additional
that are not part of a
, each of which requires a separate row in the reference set.
Example of OWL axiom refset representation of the definition of appendectomy |
id | effective Time | active | moduleId | refsetId | referenceComponentId | owlExpression |
.. | This example has not yet been released in this form and is subject to change. |
| 1 | .. | | | EquivalentClasses(:80146002 ObjectIntersectionOf(:71388002 ObjectSomeValuesFrom(:609096000 ObjectIntersectionOf(ObjectSomeValuesFrom(:260686004 :129304002) ObjectSomeValuesFrom(:405813007 :66754008))))) |
