The authors would like to thank the participants of the second REA-technology workshop (Santorini,

In the context of Software and Technology Engineering ontologies are frequently used. These can be grouped into two main categories, depending on whether they are used to describe the knowledge of a domain (domain ontologies); or they are used as software artifacts in software development processes. This paper presents some experiences and lessons learnt from the effective use of an ontology for Software Measurement, called SMO (Software Measurement Ontology). The SMO was developed two years ago as a result of a thorough analysis of the Software Measurement domain. Its use as a domain ontology is presented first, a description of how the SMO can serve as a conceptual basis for comparing international standards related to software measurement. Secondly, the paper describes several examples of the applications of the SMO as a software artifact. In particular, we show how the SMO can be instantiated to define a Data Quality Model for Web Portals, and also how it can be used to define a Domain Specific Language (DSL) for measuring software entities. These examples show the significant role that ontologies can play as software artifacts in the realm of Model-Driven Engineering and Domain-Specific Modeling. 1