$secs = ...         # seconds since Jan 1, 1970  00:00:00 GMT
  $date = &DateCalc("Jan 1, 1970  00:00:00 GMT",$secs);

##</code><code>##

  $date = &ParseDateString("epoch $secs");

##</code><code>##

  $secs = &UnixDate($date,"%s");