Hi Ahmed,
Try the below code
step1: create a type for your internal table.
TYPES: BEGIN OF t_final_output,
INCLUDE STRUCTURE bsik.
calc TYPE c.
TYPES END OF t_final_output.
Step2: declare the internal table.
<internal_table> TYPE STANDARD TABLE OF t_final_output.
there are many other ways to do the same. please try if this thing works according to your requirments.