title: What characters are allowed in the HTML Name attribute inside input tag?
body: <p>I have a PHP script that will generate <code>&lt;input&gt;</code>s dynamically, so I was wondering if I needed to filter any characters in the <code>name</code> attribute.</p>
  
  <p><s>I know that the name has to start with a letter, but</s> I don't know any other rules. I figure square brackets must be allowed, since PHP uses these to create arrays from form data. How about parentheses? Spaces?</p>