title: <link rel="shortcut icon"> validation error despite being valid
body: <p>The w3.org validator is giving me an error on the following line:</p>
  
  <pre><code>&lt;link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" /&gt;
  </code></pre>
  
  <p>This is the full error it gives:</p>
  
  <blockquote>
    <p>Line 1, Column 727: <strong>Bad value <code>shortcut icon</code> for attribute rel on element link: The string <code>shortcut</code> is not a registered keyword. The string <code>shortcut</code> is not an absolute URL.</strong> </p>
    
    <p>…f="/favicon.ico" type="image/x-icon" /<strong>></strong></p>
    
    <p>Syntax of link type valid for :</p>
    
    <blockquote>
      <p>A whitespace-separated list of link types listed as allowed on  in the HTML specification or listed as an allowed on  on the Microformats wiki without duplicate keywords in the list. </p>
      
      <p>You can register link types on the Microformats wiki yourself. </p>
    </blockquote>
    
    <p>Syntax of absolute IRI: An absolute URL.</p>
    
    <blockquote>
      <p>For example: <a href="http://example.org/hello" rel="nofollow">http://example.org/hello</a>, but not /hello. Spaces should be escaped as %20.</p>
    </blockquote>
  </blockquote>
  
  <p>What I don't understand is that I'm following the <a href="http://www.w3.org/TR/html5/links.html#rel-icon" rel="nofollow">HTML5 spec</a> which says:</p>
  
  <blockquote>
    <p>For historical reasons, the <code>icon</code> keyword may be preceded by the
    keyword "<code>shortcut</code>". If the "<code>shortcut</code>" keyword is present, it must be
    come immediately before the <code>icon</code> keyword and the two keywords must be
    separated by only a single U+0020 SPACE character.</p>
  </blockquote>
  
  <p>I see that it is suggesting the <code>%20</code> as a space, which I've tried:</p>
  
  <pre><code>&lt;link rel="shortcut%20icon" href="/favicon.ico" type="image/x-icon" /&gt;
  </code></pre>
  
  <p>But when I use this code, the error I get is nearly the same, except it starts out:</p>
  
  <blockquote>
    <p>Error Line 1, Column 729: <strong>Bad value <code>shortcut%20icon</code> for attribute rel on element link: The string <code>shortcut%20icon</code> is not a registered keyword. The string <code>shortcut%20icon</code> is not an absolute URL.</strong></p>
  </blockquote>