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()