title: Why can't I have a numeric value as the ID of an element?
body: <p>Working on a project, nearly finished and just tidying up the HTML and I find out that you're not really allowed to have an ID that is just a number-</p>
  
  <blockquote>
    <p>&lt; a> attribute "id" has invalid value "567" The attribute ID is of type ID. As described  above, it should begin with a letter and have no spaces</p>
  </blockquote>
  
  <pre><code>Good    &lt;a id="567" href="/index.html"&gt;
  Good    &lt;a id="n567" href="/index.html"&gt;
  </code></pre>
  
  <p>I can go through my code and add a letter then strip it when the value is used in my jQuery but it would be messing around I don't really need.</p>
  
  <p>Is there a reason I shouldn't be using numbers as ID's?</p>