This is used to indicate values to be deducted from the bill. They are always linked to the main bill.
To implement a deduction bill, the type must be indicated as "AB-" or Deduction in the "Bill Types" option. The prefix, number, and installment of the main bill must be entered; or, place the cursor on the main bill and enter the type relating to the deduction.
Therefore, a deduction bill can be linked to an accounts receivable bill as long as it respects the bill identification single key (Branch + Prefix + Bill Number + Bill Installment + Bill Type).
Prefix + Number + Installment + Type
FIN + 000456879 + NF
FIN + 000456879 + AB-
FIN + 000456879 A + NF
FIN + 000456879 A + AB-