title: Use of undefined constant LIBXML_HTML_NOIMPLIED
body: <p>I have just deployed some DOM Manipulation code to our staging server and am getting the error:</p>
  
  <pre><code>[PHP notice] Use of undefined constant LIBXML_HTML_NOIMPLIED - assumed 'LIBXML_HTML_NOIMPLIED'
  </code></pre>
  
  <p>I have no issues on my desktop using WAMP and cannot find any modules that appear to be related.</p>
  
  <p>Our Centos 6 server appears to be using PHP version 5.4.34 with libxml2-2.7.6-1 installed.</p>
  
  <p>I have searched our <code>php.ini</code> file and there is no mention of 'libxml' and <code>phpinfo()</code> gives me the following section for lib_xml:</p>
  
  <pre><code>libxml
  
  libXML support =&gt; active
  libXML Compiled Version =&gt; 2.7.6
  libXML Loaded Version =&gt; 20706
  libXML streams =&gt; enabled
  </code></pre>
  
  <p>Why would this constant be undefined?</p>