title: How to declare empty or not-empty dtd element
body: <p>How can I declare an element in DTD that is self-closing or contains elements? I have found the <code>*</code>-operator, but I can't verify if this can also validate empty elements.</p>
  
  <p>I have tried this, but it gives a compilation error in Visual Studio saying that the <code>EMPTY</code> element is not declared:</p>
  
  <pre><code>&lt;!ELEMENT File (Annotations|EMPTY)&gt;
  &lt;!ELEMENT Annotations (State*)&gt;
  &lt;!ELEMENT State EMPTY&gt;
  </code></pre>
  
  <p>Or I could try the following, but I can't validate if it is ok:</p>
  
  <pre><code>&lt;!ELEMENT File (Annotations?)&gt;
  ...
  </code></pre>