A document log is an ordered list of entries providing a history for any sort of media or file, just as a logfile provides a history of a computer program and a logbook provides a history of a journey. The history of a document may consist of copyright information, approvals, annotations, or any sort of metadata. This paper describes a metadata architecture using Content Based Identifiers and Document Logs that facilitates location of metadata from distributed sources, caching, ordering of log entries, and detection of changes in metadata or documents. The techniques used complement existing metadata format standards and are contrasted with storage of metadata in a file or document management system.

The Virtual Assembly Design Environment (VADE) is a virtual reality (VR) based engineering application which allows engineers to evaluate, analyze, and plan the assembly of mechanical systems. This system focuses on utilizing an immersive virtual environment tightly coupled with commercial computer aided design (CAD) systems. Salient features of VADE include: data integration (two-way) with a parametric CAD system; realistic interaction of the user with parts in the virtual environment; creation of valued design information in the virtual environment; reverse data transfer of design information back to the CAD system; significant interactivity in the virtual environment; collision detection; and physically-based modeling. This paper describes the functionality and applications of VADE. A discussion of the limitations of virtual assembly and a comparison with automated assembly planning systems are presented. Experiments conducted using real-world engineering models are also described.