magento 1.9.x столбец «позиция»

Я пытаюсь понять, какова цель столбца "position" таблицы "catalog_category_product":

      +-------------+------------------+------+-----+---------+-------+
      | Field       | Type             | Null | Key | Default | Extra |
      +-------------+------------------+------+-----+---------+-------+
      | category_id | int(10) unsigned | NO   | PRI | 0       |       |
      | product_id  | int(10) unsigned | NO   | PRI | 0       |       |
      **| position    | int(11)          | NO   |     | 0       |       |**
      +-------------+------------------+------+-----+---------+-------+

таблица catalog_category_entity:

      | Field            | Type                 | Null | Key | Default |
      +----------------------+------+-----+---------+---+
      | entity_id        | int(10) unsigned     | NO   | PRI | NULL    | | 
      |entity_type_id   | smallint(5) unsigned | NO   |     | 0       |                
      | attribute_set_id | smallint(5) unsigned | NO   |     | 0       |                
      | parent_id        | int(10) unsigned     | NO   |     | 0       |                
      | created_at       | timestamp            | YES  |     | NULL    |                
      | updated_at       | timestamp            | YES  |     | NULL    |                
      | path             | varchar(255)         | NO   | MUL | NULL    |                
      **| position         | int(11)              | NO   |     | NULL    |**                
      | level            | int(11)              | NO   | MUL | 0       |                
      | children_count   | int(11)              | NO   |     | NULL    |                
      +----------------------+------+-----+---------+----------------+