abap data conversion
p_in_k = CONV kunnr( |{ p ALPHA = IN }| ).
p_out_k = CONV kunnr( |{ p ALPHA = OUT }| ).
p_in_m = CONV matnr( |{ p ALPHA = IN }| ).
p_out_m = CONV matnr( |{ p ALPHA = OUT }| ).
p_in_b = CONV aufnr( |{ p ALPHA = IN }| ).
p_out_b = CONV aufnr( |{ p ALPHA = OUT }| ).