R12.1.3 - Projects related data in the AP_INVOICE_LINES_ALL table

Is there a write-up or white paper that explains the use of the projects related data in the ap_invoice_lines_all table?  I think I understand why they put the data in the lines table as it is analogous to the pa_expenditure_items_all table and this is where that data is in PA.

 

I have also verified that the interface suppliers invoices program still uses the PA data in the distributions table. 

 

Are they eventually going to change the interface table to use the data in the lines table?  If that happens is the plan to obsolete the data in the distributions table?