title: HTML form, multiple submit buttons, post payload ignores non-clicked buttons: Is this standard behaviour?
body: <p>Consider the following form in a HTML5 document:</p>
  
  <pre><code>&lt;form  method="post" action="http://example.com/submit/"&gt;
      &lt;button name="confirm" value="1" type="submit"&gt;Confirm&lt;/button&gt;
      &lt;button name="re-send" value="1" type="submit"&gt;Re-send code&lt;/button&gt;
      &lt;button name="cancel" value="1" type="submit"&gt;Cancel change&lt;/button&gt;
  &lt;/form&gt; 
  </code></pre>
  
  <p>Using Chrome, clicking the first button produces a request payload of <code>confirm=1</code>. Similarly the second button results in <code>re-send=1</code> and the third <code>cancel=1</code>.</p>
  
  <p>Examining the request payload server-side allows me to determine which of the three buttons were clicked (assuming only one of the three keys are present in the request payload).</p>
  
  <p>In all cases, the key:value pairs of the non-clicked buttons are excluded from the request payload. This is very useful.</p>
  
  <p>Is this behaviour (that non-clicked button key:value pairs are excluded from the request payload) standard?</p>