A similar approach to show how the various actors involved interact with the process can be taken with 'Use Case' or 'Collaboration' diagrams to define single 'uses' of the process and relate each of those to one or more actors. They can be useful in defining the high level scope of the process and defining client requirements. A simple collaboration diagram is shown below. Sequence diagrams and workflow diagrams can explore the sub-processes involved further.

We have included one simple example of how a collaboration diagram highlighted the key issues with a business process in a short case study based on Northumbria University's HR System implementation.

Some further references on Collaboration Diagrams are listed below:

UML Tutorial: Collaboration Diagrams - Robert C Martin Nov 1997
http://www.objectmentor.com/resources/articles/umlCollaborationDiagrams.pdf

UML Collaboration Diagrams - Kevin McNeish
http://archive.devx.com/codemag/articles/2002/mayjune/collaborationdiagrams/codemag-1.asp

Writing Collaboration Diagrams
http://odl-skopje.etf.ukim.edu.mk/UML-Help

You can move on from these broadbrush techniques to define actors in the process to more detailed, structured process mapping.