Subdocument invocation semantics in collaborative hyperdocuments

We informally explain a new Trellis model that incorporates colored tokens into the previously-described timed-Petri-net-based definition. We give examples of using Trellis to define protocols for Computer Supported Cooperative Work (CSCW). We then explain an interesting analog to procedure call we have developed for subdocument invocation in collaborative hyperdocuments. Trellis prototype implementations are based around a client-server architecture and interpret their specifications. Consequently they provide an environment for the rapid prototyping and incremental development of multi-user distributed protocols.