This proposal describes how data, program code, and presentation can be stored together in a single file suitable for electronic publication and permitting the reproduction of computational results.. Universality, effciency, platformindependence, automated verifiability, and provenance tracking are the major design criteria. Existing and well-tested technology is used as much as possible, the two major building blocks being the Hierarchical Data Format for storage and the Java Virtual Machine for platform-independent code representation and secure execution.