MarkupBlock - [0..20)::20 - [<!--<foo>--</bar>-->]
    MarkupCommentBlock - [0..20)::20
        MarkupTextLiteral - [0..4)::4 - [<!--] - Gen<Markup> - SpanEditHandler;Accepts:None
            OpenAngle;[<];
            Bang;[!];
            DoubleHyphen;[--];
        MarkupTextLiteral - [4..17)::13 - [<foo>--</bar>] - Gen<Markup> - SpanEditHandler;Accepts:Whitespace
            OpenAngle;[<];
            Text;[foo];
            CloseAngle;[>];
            DoubleHyphen;[--];
            OpenAngle;[<];
            ForwardSlash;[/];
            Text;[bar];
            CloseAngle;[>];
        MarkupTextLiteral - [17..20)::3 - [-->] - Gen<Markup> - SpanEditHandler;Accepts:None
            DoubleHyphen;[--];
            CloseAngle;[>];
