Markup block - Gen<None> - 16 - (0:0,0)
    Markup span - Gen<Markup> - [<!DOCTYPE html>] - SpanEditHandler;Accepts:None - (0:0,0) - Symbols:6
        HtmlSymbolType.OpenAngle;[<];
        HtmlSymbolType.Bang;[!];
        HtmlSymbolType.Text;[DOCTYPE];
        HtmlSymbolType.WhiteSpace;[ ];
        HtmlSymbolType.Text;[html];
        HtmlSymbolType.CloseAngle;[>];
    Markup span - Gen<Markup> - [ ] - SpanEditHandler;Accepts:None - (15:0,15) - Symbols:1
        HtmlSymbolType.WhiteSpace;[ ];
