Delivery service 0SD_C04 help

Question

we have activated BI content 0SD_C04 and we see routines like :
Example 1: For : Determine Determine Goods Issue Date
Update Routine is:
  IF COMM_STRUCTURE-ACT_GI_DTE IS INITIAL OR
     COMM_STRUCTURE-REQ_QTY_DL IS INITIAL OR
     COMM_STRUCTURE-REQ_DATE   IS INITIAL OR
     COMM_STRUCTURE-MATAV_DATE IS INITIAL OR
     COMM_STRUCTURE-GI_DATE    IS INITIAL OR
     COMM_STRUCTURE-DSDEL_DATE IS INITIAL OR
     COMM_STRUCTURE-SHIP_DATE  IS INITIAL.
    RETURNCODE = 4.
    EXIT.
  ENDIF.
  RESULT = COMM_STRUCTURE-ACT_GI_DTE.
  IF COMM_STRUCTURE-STORNO NE SPACE.
    RESULT = RESULT * ( -1 ).
  ENDIF.
  RETURNCODE = 0.
Why do we need this above routine. Cann't we have 1:1 mapping
Example 2: For : Net Weight in Standard Weight Unit (UNIT)
  DATA: WEIGHT LIKE COMM_STRUCTURE-NET_WGT_DL.
  IF COMM_STRUCTURE-UNIT_OF_WT NE WT_UNIT.
    WEIGHT = COMM_STRUCTURE-NET_WGT_DL.
    CALL FUNCTION 'UNIT_CONVERSION_SIMPLE'
         EXPORTING
              INPUT                = COMM_STRUCTURE-NET_WGT_DL
              UNIT_IN              = COMM_STRUCTURE-UNIT_OF_WT
              UNIT_OUT             = WT_UNIT
         IMPORTING
              OUTPUT               = WEIGHT
         EXCEPTIONS
              CONVERSION_NOT_FOUND = 1
              DIVISION_BY_ZERO     = 2
              INPUT_INVALID        = 3
              OUTPUT_INVALID       = 4
              OVERFLOW             = 5
              TYPE_INVALID         = 6
              UNITS_MISSING        = 7
              UNIT_IN_NOT_FOUND    = 8
              UNIT_OUT_NOT_FOUND   = 9
              OTHERS               = 10.
    IF SY-SUBRC NE 0.
      clear MONITOR.
      MONITOR-msgno = '009'.
      MONITOR-msgid = 'SDBW'.
        MONITOR-msgty = c_msgty_e.
      MONITOR-msgv1 = COMM_STRUCTURE-UNIT_OF_WT.
      append MONITOR.
      RETURNCODE = 4.
      WEIGHT = 0.
    ELSE.
      RESULT = WEIGHT.
      RETURNCODE = 0.
    ENDIF.
  ELSE.
    RESULT = COMM_STRUCTURE-NET_WGT_DL.
    RETURNCODE = 0.
  ENDIF.
  UNIT = WT_UNIT.
  IF COMM_STRUCTURE-DOC_CATEG CA CREDIT.
    RESULT = RESULT * ( -1 ).
  ENDIF.

Answer 1

HI,
One is date calculation, another one conversion routine,
second one converting and checking each and every step.
how can its possible for 1:1,
Thanks
Sreenu