https://docs.appian.com/suite/help/19.1/recipe_build_a_wizard_with_milestone_navigation.html
This is pattern for a form with summary at the end.
Which component exactly is responsible for generating summary view? Form Layout? Milestone?
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Are you referring to the Review step? It uses the same components as steps 1 and 2, just in read-only mode. As you can see in the code, there's a form layout containing 2 section layouts, one of which contains a milestone field.