title: COMPLETE list of HTML tag attributes which have a URL value?
body: <p>Besides the following, are there any HTML tag attributes that have a URL as their value?</p>
  
  <ul>
  <li><code>href</code> attribute on tags: <code>&lt;link&gt;</code>, <code>&lt;a&gt;</code>, <code>&lt;area&gt;</code></li>
  <li><code>src</code> attribute on tags: <code>&lt;img&gt;</code>, <code>&lt;iframe&gt;</code>, <code>&lt;frame&gt;</code>, <code>&lt;embed&gt;</code>, <code>&lt;script&gt;</code>, <code>&lt;input&gt;</code></li>
  <li><code>action</code> attribute on tags: <code>&lt;form&gt;</code></li>
  <li><code>data</code> attribute on tags: <code>&lt;object&gt;</code></li>
  </ul>
  
  <p>Looking for tags in wide usage, including non-standard tags and old browsers as well as HTML 4.01, HTML 5, and XHTML.</p>