The SysML QUDV (Quantities, Units, Dimensions and Values) modelLibrary is specified in a UML/SysML class/block diagram. In order to generalize its potential usage and alignment with other standardization efforts concerning quantities and units, it is of interest to verify that the QUDV model can also represented in the form of an ontology using a formal ontology definition language.

The QUDV model has successfully been expressed in OWL 2 (W3C Web Ontology Language v2) using the open source Protégé v4 tool,

The following screenshots shows the classes, object properties, data properties and a selection of individuals. The individuals represent some quantities, units, scales and a prefix for the International System of Quantities (ISQ) and International System of Units (SI), as defined in ISO 31 and ISO/IEC 80000. In addition inch is defined to show one non-SI unit with its conversion factor.

The ontology is split into two parts:

• SysML-QUDV which contains the basic ontology

• SysML-QUDV-SI which contains the ISQ and SI individuals

The full set of OWL/XML and Manchester OWL Syntax source code files and screenshots is available in this ZIP file sysml-qudv:qudv-owl:2009-10-27-sysml-qudv-in-protege-owl.zip.

The screenshots below from Protege provide an overview.

Asserted Class Hierarchy

Inferred Class Hierarchy

Inferred Class Tree by OWLViz

Object Properties

Data Properties

Selection of Individuals representing ISQ and SI