InterUnit Transfer between 2 Inventory Business Units with the same GL Business Unit

For an InterUnit Transfer between 2 Inventory Business Units with the same GL Business Unit, I can see the credit line information on the InterUnit Transfers Accounting page

and on the Transaction Accounting Rules page for 031 transactions.  I haven't been able to find where the debit line information is coming from.  We are not using location accounting.  Please let me know where else I should be looking for the debit line information.  Thank you!