title: What does it mean to have an at sign (@) prefixing an HTML attribute token in a JQuery selector?
body: <p>I found <a href="http://www.catswhocode.com/blog/8-awesome-jquery-tips-and-tricks" rel="nofollow">this snippet online:</a></p>
  
  <pre><code>$('a[@rel$='external']').click(function(){
    this.target = "_blank";
  });
  </code></pre>
  
  <p>What does the <code>@</code> mean though? Why <code>@rel</code> and not just <code>rel</code>? I wanted to submit a code-correction to that and I don't actually know if this is a typo or not.</p>