MarkupBlock - [0..11)::11 - [<!--Foo--> ]
    MarkupCommentBlock - [0..10)::10
        MarkupTextLiteral - [0..4)::4 - [<!--] - Gen<Markup> - SpanEditHandler;Accepts:None
            OpenAngle;[<];
            Bang;[!];
            DoubleHyphen;[--];
        MarkupTextLiteral - [4..7)::3 - [Foo] - Gen<Markup> - SpanEditHandler;Accepts:Whitespace
            Text;[Foo];
        MarkupTextLiteral - [7..10)::3 - [-->] - Gen<Markup> - SpanEditHandler;Accepts:None
            DoubleHyphen;[--];
            CloseAngle;[>];
    MarkupTextLiteral - [10..11)::1 - [ ] - Gen<Markup> - SpanEditHandler;Accepts:None
        Whitespace;[ ];
