Besides areas of responsibilities and specific activities, business activity diagrams can also show business entities being manipulated in the activities.
- Business entities represent objects that are either created, updated or used during the course of the business activity.
- Things like customer profile, paycheck, order, etc.
If you model the business with the goal of eliciting better system requirements, some of these business entities will become analysis classes in your system design, in essence reusing the business artifacts in the design of the system.
This diagram shows the business entities (aProposal, a Quote, aPlan) and their states (created/complete).