OK so you want to determine which specification codes to use when printing an invoice with a portion retained for later? This makes sense.

I have a feeling you can get some but not all of the information you listed here. This is because Adagio Invoices likely does not keep track of 'previously applied' invoices as you indicated.

So let's use numbers as part of an example: You have an invoice for $100.00, of which 10% (or 10.00) will be retained. Are these the numbers you need?:

Subtotal: 100.00 (maybe M7)
Total Complete: 100.00 (maybe E58) - how is this different than Subtotal?
Retainage: 10.00 (E60)
Total earned less ret: 90.00 (E61)

Previously applied - where would you see this in the system? That would help to identify what is possible. If from another invoice, then you won't be able to print this. Maybe this could be an optional field (manually entered) which can be printed in the Totals section.

Payment Due - Likely this field doesn't exist either, needing a calculation from above. Unless a different optional field is used...