Context Handlers (not to be confused with the context type) define a modification on the context stack, whenever the rule of the corresponding event matcher applies. There are currently two styles of context handlers:

          !Push
          # or
          !ReplacePush
        

Example:

          contexts:
            - !Context
              name: headline
              defaultHandler:
                !Handler
                eventMatcher: ...
                contextHandler: !Push { writeCharacters: true }
                ...