So to encode a xml fragment like this
string s="[formbody xmlns="http://www.Foo.com/FormBody"][/formbody]"
We should have to write as follows using verbatim character and Quote escape sequence
string s = @"[FormBody xmlns=""http://www.Foo.com/FormBody""][/FormBody]";
but C# handles this quote-escape-character as regular escape sequence internally

For more Check the C# language Specification