Markup block - Gen<None> - 7 - (0:0,0)
    Markup span - Gen<Markup> - [foo baz] - SpanEditHandler;Accepts:Any - (0:0,0) - Symbols:3
        HtmlSymbolType.Text;[foo];
        HtmlSymbolType.WhiteSpace;[ ];
        HtmlSymbolType.Text;[baz];
