Proposal for a quantity based data model in the Virtual Observatory

We propose the beginnings of a data model for the Virtual Observatory (VO) built up from simple ``quantity'' objects. In this paper we present how an object-oriented, domain (or namespace)-scoped simple quantity may be used to describe astronomical data. Our model is designed around the requirements that it be searchable and serve as a transport mechanism for all types of VO data and meta-data. In this paper we describe this model in terms of an OWL ontology and UML diagrams. An XML schema is available online.