"Sequence Diagrams" are commonly used in software engineering to describe the flow of a piece of software. One often finds that a sequence diagramme can really help to describe a program's flow to another person or can be a real help as an aid to reading third-party code. Sequence Diagrammes are definitely not well suited to completely describing a piece of software. A tool like this is not trying to replace source code!
Sequence Sketcher is currently in development and this is a beta version of the software. You are welcome to test it and use it on any number of computers in your organisation until 1st November 2001. After this date you will be required to discontinue use of the product, purchase a copy of the software or download a new beta. A software-license-key has been provided with SequenceSketcher.