used values for your city are correct, select the Continent/City or fill the timezone string and submit -- you can then check that the week, week day, month, hour and minute of the DST start and end time are correct.<br>
Some values, when absent, have a default value; consult the 'tzset' Linux manual page for more details, or read the <a href="http://pubs.opengroup.org/onlinepubs/007904875/basedefs/xbd_chap08.html">TZ variable</a> specification (look near the end).

<p>If the box has internet access you can