PARAMETERS:
  p_vbeln    type char10,
  p_posnr    type char6, " matchcode object WTY_F4_VBAP-POSNR,
  p_layout   type  disvariant-variant.

AT SELECTION-SCREEN ON VALUE-REQUEST FOR p_vbeln.
  perform vbeln_value_request changing p_vbeln.

AT SELECTION-SCREEN ON VALUE-REQUEST FOR p_posnr.

form VBELN_VALUE_REQUEST  changing pp_vbeln.
  data: itab_return   type standard table of ddshretval,
        wa_return     type ddshretval,
        SHLP_DESCR    type SHLP_DESCR,
        dynpfields    LIKE dynpread OCCURS 1 WITH HEADER LINE.

  FIELD-SYMBOLS: <fs> like line of SHLP_DESCR-interface.

    CALL FUNCTION 'F4IF_GET_SHLP_DESCR'
      EXPORTING
        SHLPNAME       = 'WTY_F4_VBAP'
      IMPORTING
       SHLP           = SHLP_DESCR.

    LOOP AT SHLP_DESCR-interface ASSIGNING <fs>.
      <fs>-valfield = '~'.
    ENDLOOP.

    CALL FUNCTION 'F4IF_START_VALUE_REQUEST'
      EXPORTING
        SHLP                = SHLP_DESCR
      TABLES
        RETURN_VALUES       = itab_return.

  if sy-subrc <> 0.
    message id sy-msgid type sy-msgty number sy-msgno
            with sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
  else.
    loop at itab_return into wa_return.
      case wa_return-fieldname.
        when 'VBELN'.
          pp_vbeln = wa_return-fieldval.
        when 'POSNR'.
          p_posnr = wa_return-fieldval.
      endcase.
    endloop.
  endif.

  REFRESH dynpfields.
  CLEAR   dynpfields.
  dynpfields-fieldname  = 'P_VBELN'.
  dynpfields-fieldvalue = p_vbeln.
  APPEND dynpfields.
  dynpfields-fieldname  = 'P_POSNR'.
  dynpfields-fieldvalue = p_posnr.
    APPEND dynpfields.

  CALL FUNCTION 'DYNP_VALUES_UPDATE'
    EXPORTING
      dyname     = sy-repid    "Program name
      dynumb     = sy-dynnr      "Screen number
    TABLES
      dynpfields = dynpfields
    EXCEPTIONS
      OTHERS     = 0.
endform.                    " VBELN_VALUE_REQUEST