title: Is it illegal to have unused namespace declarations in an XML document?
body: <p>For instance, is the following XML document considered valid as per the W3C XML 1.0 recommendation?  Notice that the namespace 'future' is not referenced anywhere in the document.</p>
  
  <p>Although this may not be considered good style, my belief is that the document is still valid regardless of the unused namespace.   Can anyone confirm or refute this assumption?</p>
  
  <p>Thanks, Matt</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8" ?&gt;
  &lt;root xmlns='http://foo.org/v1'  xmlns:future='http://bar.org/v1'&gt;
      &lt;child&gt;1&lt;/child&gt;
  &lt;/root&gt;
  </code></pre>