Interactions are collaborative actions carried out by two or more roles. Let’s take some examples:
The purchaser arranges finance with their bank.
The Project Manager and Line Manager review the Project Plan.
The QA Team lets the Project Manager know they have finished the tests.
The Line Manager asks for an update on progress.
Vendor and Purchaser agree on the delivery date.
The Sales Executive tells the Project Team of the contract change.
The Product Design Team gives the Development Team the specification.
The Engineering Department drafts the design with the Production Engineer.
All the Divisional Managers meet to review the budgets.
Each Divisional Manager reports to the Board.
A vanilla interaction between roles is shown ...