MarkupBlock - [0..5)::5 - [<foo>]
    MarkupTagBlock - [0..5)::5 - [<foo>]
        MarkupTextLiteral - [0..5)::5 - [<foo>] - Gen<Markup> - SpanEditHandler;Accepts:None
            OpenAngle;[<];
            Text;[foo];
            CloseAngle;[>];
