($ayear, $amonth, $valid) = nextmonth($year, $month, $config{archivebase});
$affected{calendarlink($ayear, sprintf("%02d", $amonth))} = sprintf(gettext("building calendar for %s/%s, its previous or next month has changed"), $amonth, $ayear) if ($valid);
($ayear, $amonth, $valid) = previousmonth($year, $month, $config{archivebase});
($ayear, $amonth, $valid) = nextmonth($year, $month, $config{archivebase});
$affected{calendarlink($ayear, sprintf("%02d", $amonth))} = sprintf(gettext("building calendar for %s/%s, its previous or next month has changed"), $amonth, $ayear) if ($valid);
($ayear, $amonth, $valid) = previousmonth($year, $month, $config{archivebase});