Link between transaction to Inventory detail Page

I want to set a default value of an inventory status, at an 'inventoryassignment' sublist of an Inventory Detail. I cannot find any link betwwen the inventory detail or the 'inventoryassignment' sublist to the transaction or to its type, at the following Netusite documentation:

https://www.netsuite.com/help/helpcenter/en_US/srbrowser/Browser2020_2/script/record/inventorydetail.html

There must be a link between the inventory detail popup to the transaction and the transaction line it associated with. Do someone know how it is done? or there is any other link for a relevant documentation?

Thanks in advance.