The supporting section covers features that don't belong to the core request cycle but are used throughout a typical application.
routeLink(), em(), ca(), s(), _t(), form helpers, and time functions_t() and _tt(), locale file format, adding new languages, and how the Translator class worksAbstractEventsDispatcher, AbstractEventListener, AbstractEventSubscriber, and hooking into middleware eventsCrudControllerInterface contract, method signatures, expected HTTP status codes, and a reference implementation