title: URL starts with a double slash
body: <p>On several pages I saw in the last months following syntax for a address</p>
  
  <pre><code>&lt;a href="//mynextpage.html"&gt;...&lt;/a&gt;
  </code></pre>
  
  <p>What does this way of an url stay for? Is it a kind of wildcard for the protocol you have called this site?</p>