title: what does data-url attribute in the <form> tag mean?
body: <p>All,</p>
  
  <p>Recently I found out some HTML source for a user registration, a form like below:</p>
  
  <pre><code>&lt;form action="/users" class="signup-form" data-url="/users/current" id="new_user" method="post"&gt;
      &lt;input id="user_user_name" name="user[user_name]"&gt;
      &lt;input id="user_password" name="user[password]"&gt;
  
      &lt;input id="create-account-button" name="commit" type="submit" value="Create Account" /&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>My question is:</p>
  
  <p>1) what does data-url here mean? 
  2) why put input field name as user[user_name], user[password] this kind of format? Shouldn't make the input name just as 'user_name' and 'password' easier?
  I mean, this must relate to a data model user, so naming in this way will be better for server processing.</p>
  
  <p>Could anyone tell me if this is new HTML feature or jQuery feature? I did lots of search online, but I couldn't find out answer. Could you pelase give me any link or tutorial for this new html format submission?</p>
  
  <p>Many thanks.
  Sam</p>