The issues of portability and re-use are key challenges for learning technology. A major effort has been directed toward the development of standards that will enable interoperability and the re-use of learning objects. This paper provides a critique of this work from a pedagogical perspective. It argues that true portability and re-use cannot be achieved based solely on a technically inspired drive towards standardization. A theoretical framework is required that will guide the process of analysis and synthesis. The paper proposes the basis for such a theoretical approach based on the concepts of layering and learning contexts. A formal approach to capturing the essential features of these learning contexts is outlined, based on the idea of design action potential networks. The choice pathways in these networks represent a formal description that may be fed into the standardization process. The ensuing descriptive data, attached as metadata to learning objects, would provide a pedagogically informed basis for interoperability and re-use. (Contains 18 references.) (Author/MES)