CTX Addenda

Has anyone ever had to add data in the CTX file mapping for an addendum?  If so what fields map to the section in the CTX file?

Let $BPR = 'BPR'

   Let $BPR01 =
'C' !Payment

   let $BPR02 =
to_char(#Ttl_Paid_Amt_Gross)

   let $BPR03 = 'C'
!Credit

   let $BPR04 = 'ACH'
!Automated Clearing House

   let $BPR05 = 'CTX'
!Payment Format

   let $BPR06 = '01'

   let $BPR07 = $ISA06

   let $BPR08 =
'DA'  !Account Qualifer = DA Demand Deposit

   let $BPR09 =
'11111'

   let $BPR10 =
$CTX_Payer_ID

   let $BPR11 = '*'
!Place Holder - not used

   let $BPR12 = '01'

   let $BPR13 =  $CTX_Payer_Bank_WO_Cd