The evolving complexity of many modern artifacts, such as aircraft, has led to a serious fragmentation of knowledge among software systems required for their design and manufacture. In the case of aircraft design, views of the same generic design knowledge are redundantly encoded in multiple software systems, each system using its own idiosyncractic ontology, and each system containing that knowledge in an implicit, taskand vendor-specific form. This situation is expensive, due to high cost of developing from scratch, maintaining and keeping synchronized the many systems used in design. Boeing’s "Neutral Representation" project aims to address these concerns by prototyping languages and methods for making these underlying ontologies and knowledge explicit, and hence more sharable and maintainable. We are approaching this goal through three tasks: Building explicit, neutral, machinesensible representations of design knowledge; structuring that knowledge into reusable components, indexed by the ontologies which they use; and linking those representations with existing design systems. In this paper we present the work done this year, and discuss issues related to ontological engineering and knowledge sharing which have arisen.