1. contracts - agreements among initiators and participants
2. Initiator - executes actions which require services
3. Participant - provides services through an interface to initiators
4. Service - behavior of a participant in response to a request
5. Glossary - list of occurrences of elements
6. Attribute - name/value set in which states are described.
7. Script - specification of flow of actions initiated by outside agent.
8. Event - phase change in script