title: How should User Agents deal with non-integer values for tabindex and z-index?
body: <p>I have some code I'm supporting that has <code>tabindex="1.1"</code>, <code>tabindex="1.2"</code>, etc. I'm thinking about changing the values to be integers. Would this improve browser behaviour?</p>
  
  <p><a href="http://www.w3.org/TR/html401/interact/forms.html#tabbing-navigation" rel="nofollow">W3C says</a>:</p>
  
  <blockquote>
    <p><strong>tabindex</strong> = <em>number</em> [CN]</p>
    
    <p>This attribute specifies the position of the current element in the tabbing order for the current document. This value must be a number between 0 and 32767. User agents should ignore leading zeros.</p>
  </blockquote>
  
  <p>It doesn't say how non-integer values should be treated.</p>
  
  <p><a href="http://www.docbook.org/tdg/en/html/ref-elements.html" rel="nofollow">This reference</a> says:</p>
  
  <blockquote>
    <p>NUMBER</p>
    
    <p>A number. Numbers must begin with a hyphen or digit and can include the decimal point.</p>
  </blockquote>
  
  <p>So the markup is valid if you use a decimal point but does it make sense?</p>
  
  <p>My question is should user agents honour the decimal point and the digits after it or just use the integer part? i.e. should the two values above be treated as the same or different? Why would you use those values in favour of <code>tabindex="11"</code>, <code>tabindex="12"</code>, etc.? The same goes for z-index.</p>