Identify the use case
This initially involves background analysis to come up with suggestions for the different ways users may interact with the system.
Pick up a few "focal" use cases that represent critical interactions.
Then, work on these focal use cases by elaborating their steps with cards and role-play.
After that, select a card and begin to work out the dialogue.
The team works together on determining the steps in the dialogue. When ideas seem reasonable, the role-players "play-out" through the script, as shown in the figure below.
Figure 5. A team performing use case roleplay while others review the dialog
After the index and role-play have helped determine the use case bodies, the full details may be recorded in requirements documentation or in CASE tool databases.