What is $link value of hasMany() when use with viaTable()

From hasMany() documentation




public function getOrders()

{

    return $this->hasMany(Order::className(), ['customer_id' => 'id']);

}



customer_id is a column of Order class.

id is a column of Customer class.

From viaTable() documentation




public function getItems()

{

    return $this->hasMany(Item::className(), ['id' => 'item_id'])

                ->viaTable('order_item', ['order_id' => 'id']);

}



Which class does id of hasMany() belongs to? Is it Order or Item?

Which class does item_id of hasMany() belongs to? Is it Order or Item?