This article outlines the database structure for the MMv4 category_attr_node database table. This table contains the values of any custom category fields with the type of: list_single, list_multi, dropdown or radio.

• id
  Primary Key of the table.
  int(10) | unsigned | auto increment | primary key | indexed
• display_order
  The order in which the nodes will be displayed in the menu. Any nodes that have the same display_order value will then order by title in ascending order.
  int(10) | unsigned | indexed
• title
  Descriptive title of the node. This will be displayed as the selectable option in any form field in which the node is included.
  varchar(255)
  
• selected_value
  This is the actual value that is recorded in the database when the node is selected. This may be either the same or different than the "title". If left blank, then the system will reuse the "title" as the "value".
  varchar(255)
  
• container_id
  Reference to the category_attr.id that this node is associated with.
  int(10) | unsigned | indexed