Can anybody explain me

Question

can anybody explain me
FORM availability_check USING  fp_i_orderdata TYPE ty_t_orderdata
                      CHANGING fp_v_selfield  TYPE slis_selfield .
Local data declarations
  FIELD-SYMBOLS <l_fs_orderdata> TYPE ty_orderdata.
Loop at the order data
  LOOP AT fp_i_orderdata ASSIGNING <l_fs_orderdata>
                             WHERE selected = c_x.
Perform availability check on selected order
    IF <l_fs_orderdata> IS ASSIGNED.
      PERFORM avt_chk_onorder USING <l_fs_orderdata>-aufnr.
    ENDIF.
  ENDLOOP.
If no orders were selected
  IF sy-subrc <> 0.
Please select at least 1 order
    MESSAGE e095.
  ENDIF.
Get the data for orders on which mass availability
check may be done, for the selection criteria.
  REFRESH i_orderdata.
  PERFORM get_orderdata CHANGING i_orderdata.  " Order data
Update refresh indicator
  fp_v_selfield-refresh = c_x.

Answer 1

what explaination do you want .
This form is form availability check which is getting an input of table of order data looping though that doing a check for order for availibilty .
Then on delcompletion flag the fp_v_selfield .
If the earlier loop at no orders selecled then throw an erro message .
Please reward if useful.