CCalendar::SaveUserTimezoneName

static function SaveUserTimezoneName($user, $tzName = '')
{
	if (!is_array($user) && (int)$user > 0)
	{
		$user = self::GetUser($user, true);
	}

	CUserOptions::SetOption("calendar", "timezone".self::GetCurrentOffsetUTC($user['ID']), $tzName, false, $user['ID']);
}