title: Get XML namespace of root node
body: <p>I receive xml like:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;?xml-stylesheet type="text/xsl" href="http://adress.pl/FeResourceServlet/localTemplate/template1/styl.xsl"?&gt;
  &lt;wnio:Dokument 
  xmlns:adr="http://adress.pl/xml/schema/adress/2009/11/09/" 
  xmlns:ds="http://www.w3.org/2000/09/xmldsig#" 
  xmlns:ev="http://www.w3.org/2001/xml-events" 
  xmlns:inst="http://adress.pl/xml/schematy/instytucja/2009/11/16/" 
  xmlns:meta="http://adress.pl/xml/schematy/meta/2009/11/16/" 
  xmlns:oso="http://adress.pl/xml/schematy/osoba/2009/11/16/" 
  xmlns:str="http://adress.pl/xml/schematy/struktura/2009/11/16/"      xmlns:wnio="http://epuap.gov.pl/FeResourceServlet/localTemplate/ZgloszenieBudowy/" 
  xmlns:xf="http://www.w3.org/2002/xforms" 
  xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xmlns:xxforms="http://orbeon.org/oxf/xml/xforms"
  xsi:schemaLocation="http://adress.pl/FeResourceServlet/localTemplate/template1/ http://epuap.gov.pl/FeResourceServlet/localTemplate/template1/schema.xsd"&gt;
  ...
  </code></pre>
  
  <p>My question is - How can I get a namespace of root? 
  Above my root node is wnio:Dokument and I know that wnio is "namespace of root" and name of root is Dokument.</p>
  
  <p>But name and namespace can be changed. Then I will have root node but I wouldn't know namespace and name of root.</p>
  
  <p>I used so far: SimpleXMLElement::getNamespaces and SimpleXMLElement::getDocNamespaces. But I received every namespace but I don't know which is root. </p>
  
  <p>It's possible in PHP to get these information?</p>