The digital parts libraries or electronic parts catalogs have opened up a vast potential for new electronic forms of product components procurement. However, their seamless integration is impeded by the mismatches of their ontologies. The origin of the ontology mismatches is the differences in the way the given domain is interpreted (conceptualized). In this paper, we discuss content-oriented knowledge modeling of parts libraries. We propose a system of meta-concepts which have explicit ontological semantics. The explicit ontological semantics helps ontology developers to consistently and systematically interpret the parts library knowledge. We also discuss an experimental application of our proposal to a real case of mold and die parts libraries.