title: mktime and tm_isdst
body: <p>I saw a lot of different views so thought of asking here.</p>
  
  <p>I read <code>man mktime</code>:</p>
  
  <pre><code> (A positive or zero value for tm_isdst causes mktime() to presume initially
   that summer time (for example, Daylight Saving Time) is or is not in
   effect for the specified time, respectively.  A negative value for
   tm_isdst causes the mktime() function to attempt to divine whether summer
   time is in effect for the specified time. 
  </code></pre>
  
  <p>My question is, shouldn't <code>tm_isdst</code> be kept as <code>-1</code> to let the system decide if its dst or not and that way the code becomes dst agnostic? </p>
  
  <p>Am I missing something?</p>