<p><pre><code>  But the data itself is not new software. It is just data. 
  Functionality should not change because of new data.
</code></pre>
Well, <i>ideally</i>, yes. But software breaks all the time when you give it data the programmer didn&#x27;t expect, which happens especially often with time.<p>DST, for example. What if a state <i>stops</i> observing DST? Arizona observed DST in 1967, but hasn&#x27;t since then. A couple other states are considering abolishing it, too. You can easily imagine software doing something dumb when it can&#x27;t find its DST entry in tzdata.