What is the sort order rule of Kit components in sales order

Summary:

Fusion 26A, sort order of kit components is not line_id, fulfill_line_id nor item_id. However the sales order screen shows always the same order. Could you tell what is the rule?

Content (please ensure you mask any confidential information):

Hello.

When input Kit item in sales order, we can see the detail of the kit item. Kit components are shown in detail screen, but the same kit number appears different sort order in the different sales order. It is not random order, since whenever I opened the screen, the same order number shows always the same order of kit components.