MarkupBlock - [0..9)::9 - [<!--<foo>]
    MarkupTextLiteral - [0..9)::9 - [<!--<foo>] - Gen<Markup> - SpanEditHandler;Accepts:None
        OpenAngle;[<];
        Bang;[!];
        DoubleHyphen;[--];
        OpenAngle;[<];
        Text;[foo];
        CloseAngle;[>];
