Use
If you use the During Processing of Employee Data processing time to process blocks, structures, and fields in your user-defined form routine, the data can be used as defined in the interface format. The Interface Toolbox generates coding that represents the internal tables, infotypes, and field strings from the interface format.
The coding for the interface format data is defined in the first include used to generate the conversion program for the file layout. If you use this include in the program containing the user-defined form routine, the interface format data can be called up in the form <table name>-<field name>. You can also use the standard table operations used in the Advanced Business Application Programming (ABAP) language, for example, LOOP, READ TABLE, and so on.

For example, if you have specified that the NACHN, VORNA and GESCH fields from infotype P0002 (Personal Data) are used, the Interface Toolbox generates the following coding:
DATA: BEGIN OF P0002 OCCURS 5,
NACHN(000025) TYPE C,
VORNA(000025) TYPE C,
GESCH(000001) TYPE C,
END OF P0002.
You can now use the names of the fields defined above (NACHN, P0002-VORNA, and P0002-GESCH):
REPORT ZUSER_EXITS.
INCLUDE ZPCIFT01.
FORM EXAMPLE_P0002 USING PAR_01
PAR_02
PAR_03
PAR_04
PAR_05
PAR_06
PAR_07
PAR_08
PAR_09
PAR_10
PAR_11
PAR_12
PAR_13
PAR_14
PAR_15
RETURN_VALUE.
READ TABLE P0002 INDEX 1.
CONCATENATE P0002-NACHN
P0002-VORNA
INTO RETURN_VALUE
SEPARATED BY `,`.
ENDFORM.
Legend
If the first line of infotype P0002 (Personal Data) contains the first name (P0002-VORNA) ’James’ and the surname (P0002-NACHN) ’Bond’, then the return value is the character string ‘Bond, James’.
If the system processes a new payroll period, the Interface Toolbox enters the corresponding payroll period values in the interface format data.

You can also transfer infotype P0002 (Personal Data) directly in parameters 1 to 15, instead of following the above example.