title: How to make a radio button read-only but not disabled?
body: <p>The question "How to make radio button read-only?" has already been asked <code>n</code> times. But the solution is always <code>disabled="disabled"</code>.</p>
  
  <p>(There can also be complicated JavaScript solutions, that work with the <code>click</code> or <code>change</code> event and prevent the value's change, but all that has usually a smell of a more or less dirty hack.)</p>
  
  <p>The problem / side effect of <code>disabled="disabled"</code> is, that it "removes" the field from the data set and it then isn't sent to the server.</p>
  
  <p>What I want is to make the radio buttons read-only / not changeable -- but in the same time to let them be sent to the server on form submit. <code>disabled</code> doesn't meet this requirement, <code>readonly</code> seems not to work for radio buttons.</p>
  
  <p><strong>What is the correct HTML attribute for making a radio button read-only without to remove it from the form data set?</strong></p>