EventSubscribers should be allowed in Extension objects.

For example, if I want to extend the Check Report to have an Amount column formatted in a different way.

reportextension 99900 "Check" extends Check

{

    dataset

    {

        add(PrintCheck)

        {

            column(CustomFormatAmount; CustomFormatAmount) { }

        }

    }

    [EventSubscriber(ObjectType::Report, Report::Check, 'OnAfterFormatNoText', '', false, false)]

    local procedure Testing(No: Decimal)

    begin

        CustomFormatAmount := format(No, 0, 'Some format string');

    end;





    var

        CustomFormatAmount: Text;

}

This is not allowed because you can't call the event subscriber from the extension object.