title: Is 'en-EU' a valid value for HTML 'lang' attribute?
body: <p>Markup for different editions of my news site...</p>
  
  <ul>
  <li><p>US Edition:</p>
  
  <pre><code>&lt;html lang="en-US" xml:lang="en-US"&gt; ... &lt;/html&gt;
  </code></pre></li>
  <li><p>India Edition:</p>
  
  <pre><code>&lt;html lang="en-IN" xml:lang="en-IN"&gt; ... &lt;/html&gt;
  </code></pre></li>
  <li><p>Europe Edition (in this case not a specific country, i.e. news covers a broader region):</p>
  
  <pre><code>&lt;html lang="en-EU" xml:lang="en-EU"&gt; ... &lt;/html&gt;
  </code></pre></li>
  </ul>
  
  <p>I am depending on the markup of the page to make the target language/region of pages clear to the search engines because the different editions of the news site use a directory-based path (e.g. <code>example.com/eu/</code>) rather than a sub-domain (<code>eu.example.com</code>) or domain (e.g. <code>example.eu</code>) based path.</p>
  
  <p>Now coming to the point, the <code>lang</code> attribute can have a value that is of the format <em><code>language-region</code></em>. But is <code>en-EU</code> a valid value?</p>
  
  <p><strong>PS:</strong> I think so, but I'd like to confirm with the knowledgeable folks here.</p>
  
  <ul>
  <li><p>Based on: <a href="http://www.iana.org/assignments/language-subtag-registry/language-subtag-registry" rel="noreferrer">http://www.iana.org/assignments/language-subtag-registry/language-subtag-registry</a></p></li>
  <li><p>Via: <a href="http://www.w3.org/International/articles/language-tags/" rel="noreferrer">http://www.w3.org/International/articles/language-tags/</a></p></li>
  </ul>