You can read more about the Discovery pattern on the Microsoft Dynamics NAV design patterns wiki at https://community.dynamics.com/nav/w/designpatterns/271.discovery-event.
You can see some examples of this pattern in the Business Central base application in the following objects:
- Page 1808 (Assisted setup):
- OnRegisterAssistedSetup()
- Page 1500 (Workflows):
- WorkflowSetup.InitWorkflow()