Coding in user exit in program rffous_t

Question

The ACH file generated has to be updated with company specific information required by the NACHA file format standards. SAP functionality will be used to generate the interface file. 
The ACH file will contain all employees who have pay for the current pay period being processed and have direct deposit set up for the current pay period.  The ACH file will run during the biweekly and monthly payroll runs.This file will be generated upon completion of the current payroll processing.
The user-exits are invoked when the RFFOUS_T program is executed.For each record type, use the mentioned user-exit below:
•     1 (File Header Record)
o     EXIT_100
o     Function Module EXIT_RFFOEXIT_100
•     5 (Batch Header Record)
o     EXIT_101
o     Function Module EXIT_RFFOEXIT_101
•     8 (Batch Control Record)
o     EXIT_105
o     Function Module EXIT_RFFOEXIT_105
Based on the account id (REGUH table-HKTID field), the other fields have been identified.
Record Type "1"          
File ID (Immediate Origin) - Structure DTAMUSFH, Component FH4     
Origination Bank (immediate destination name) - Structure DTAMUSFH,Component FH11
Company Name (immediate origin name) - Structure DTAMUSFH, Component FH12
Record Type "5"                         
Company Name - Structure DTAMUSBH, Component BH3     
Company Discretionary Date - Structure DTAMUSBH, Component BH4
Company ID - Structure DTAMUSBH, Component BH5     
Company Entry Description - Structure DTAMUSBH, Component BH7
Company Descriptive Date - Structure DTAMUSBH, Component BH8
Effective entry date - Structure DTAMUSBH, Component BH9
Record Type "8"     
Company ID - Structure DTAMUSBC, Component BC7     
Message Authentication Code - Structure DTAMUSBC, Component BC8
Can somebody please advice me after reading the above information that how should i proceed for the coding to be done inside the user exit!!

Answer 1

Hi Bhaskar,
1. Go to CMOD(transaction) create an enchancement project .
2. enter the project name ZName and click create and enter the short description of the project.
3.now click on the enhancement assigment button on the application tool bar and enter the enhancement number: RFFOX100 (File Header Record),RFFOX101(Batch Header Record), RFFOX105(Batch Control Record).
4.now select the first enhancement number i'e RFFOX10 and click on the components it will show you the fuction module exit EXIT_RFFOEXIT_100.
5.double click on it it will take you to the fuction builder screen now click on the include it will show you the warrining 'Program names ZX... are reserved for includes of exit function groups' just ignore the warning and press enter after placing your coursour on the include, system asks to create the include press yes.
6..and now in the include code your logic to update The ACH file generated has to be updated with company specific information required by the NACHA file format standards as per your needs.
follow the procedure from 4 to 6 to populate Batch Header Record and Batch control record in the exits EXIT_RFFOEXIT_101and
EXIT_RFFOEXIT_105 respectively.
thanks and Regards,
pavankumar