title: XML what does that question mark mean
body: <p>I know XML documents usually start with something like:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  </code></pre>
  
  <p>My question is regarding the <code>&lt;?</code> and <code>?&gt;</code> what do they mean on their own?
  As in what does:</p>
  
  <pre><code>&lt;?Any old text?&gt;
  </code></pre>
  
  <p>mean in XML</p>
  
  <p>Thanks</p>