Uses IntlDateFormatter including timezone offset and DST.
see ICU Dates and Times Patterns

1. Timestamp

{{timestamp}}

/action/timestamp.php

<?php

$time        = time();
// global date & time pattern: $this->db->date_format . ' ' . $this->db->time_format or 
// localized date pattern: $this->date_format_pattern()  . ' ' . $this->db->time_format
$pattern    = 'dd.MM.y HH:mm'; 
$tpl->timestamp = $this->date_format($time, $pattern);
	

/action/template/timestamp.tpl

[ ' timestamp ' ]

2. Calendar week

{{cw}}

/action/cw.php

<?php

$time        = time();
$pattern    = 'ww';
$tpl->week = $this->date_format($time, $pattern);
	

/action/template/cw.tpl

[ ' week ' ]