Using the Data Transfer Data Structure 

If you want to write data to a batch input session or to process the data using CALL TRANSACTION USING or CALL DIALOG , you must prepare an internal table <bdc_tab> . This internal table must be structured according to ABAP Dictionary structure BDCDATA. The internal table <bdc_tab> stores the data that is to be entered into R/3 System and the actions that are necessary to process the data. You can think of the table as storing the script that the R/3 System is to follow in processing batch input data.

The graphic below shows how to declare the internal table <bdc_tab> in your ABAP program and the fields contained in the structure BDCDATA.

1. Declare internal table <bdc_tab> .
2. Initialize the internal table before you call each new transaction.
3. At the beginning of each new screen, you must maintain the module pool name <program> , the screen number <dynpro> and a flag:
   
   < bdc_tab>-PROGRAM = <program>.
   <bdc_tab>-DYNPRO = <dynpro>.
   <bdc_tab>-DYNBEGIN = 'X'.
   APPEND <bdc_tab>.
4. For each field to which you want to assign values, insert an entry in the internal table. Specify the technical field name <fnam> and the field content <fval> :
   
   <bdc_tab>-FNAM = <fnam>.
   <bdc_tab>-FVAL = <fval>.
   APPEND <bdc_tab>.
   
   If the field is in a step loop or a table control, you must also specify the lines in which the input is to be entered. The field name extension displays the line number:
   
   <bdc_tab>-FNAM = 'fieldx(5)'.
5. If you want to position the cursor on a particular field, enter the cursor position by filling field FNAM with the value BDC_CURSOR, and transferring into the field FVAL the technical name <tname> of the field where the cursor should be:
   
   <bdc_tab>-FNAM = 'BDC_CURSOR'.
   <bdc_tab>-FVAL = <tname>.
   APPEND <bdc_tab>.
   If you want to position the cursor on a field in a step loop or table control, you must also specify the lines in which the input is to be entered. The field name extension displays the line number:
   
   <bdc_tab>-FVAL = 'fieldx(5)'.
6. Now specify which action is to be executed in this screen. You must determine the triggered function code <fcode> and assign this with the field FVAL . Note that the character ' / ' should always be placed before the function key number. The character ' = ' must be placed before all other function codes.
   Assign value BDC_OKCODE to the field FNAM :
   
   <bdc_tab>-FNAM = ‘BDC_OKCODE’.
   <bdc_tab>-FVAL = <fcode>.
   APPEND <bdc_tab>.
7. Execute steps 3 to 6 for each additional screen in the transaction.

8. After the last screen in the transaction, internal table <bdc_tab> is filled with all of the values required. You can now use this table to create an entry in a batch input session or to call the commands CALL TRANSACTION or CALL DIALOG .
   The transaction to which a BDCDATA structure refers is identified separately. If your program writes data to a batch input session, then the transaction is specified in the call to the BDC_INSERT function module. This function module writes a BDCDATA structure out to the session. If your program processes data with CALL TRANSACTION USING, then the transaction is specified directly in this statement.