CCalendar::WeekDayByInd

static function WeekDayByInd($i, $binv = true)
{
	if ($binv)
	{
		$arDays = ['SU', 'MO', 'TU', 'WE', 'TH', 'FR', 'SA'];
	}
	else
	{
		$arDays = ['MO', 'TU', 'WE', 'TH', 'FR', 'SA', 'SU'];
	}
	return $arDays[$i] ?? false;
}