title: Parseing XML by R always return XML declaration error
body: <p>I am new to XML. 
  i downloaded a XML file, called ipg140722,from google drive, <a href="http://www.google.com/googlebooks/uspto-patents-grants-text.html" rel="nofollow">http://www.google.com/googlebooks/uspto-patents-grants-text.html</a>
  , I used Window 8.1,  R 3.1.1,   </p>
  
  <pre><code>library(XML)
  url&lt;- "E:\\clouddownload\\R-download\\ipg140722.xml"
  indata&lt;- xmlTreeParse(url)
  
  XML declaration allowed only at the start of the document
  Extra content at the end of the document
  error: 1: XML declaration allowed only at the start of the document
  2: Extra content at the end of the document
  
    what is the problem
  </code></pre>