Can you help me interpret the following lines in UPDATE rule?

Question

Hi,
Can you help me interpret the following lines in UPDATE rule?
1. What is the role of role of u201CCHANGING RESULT.u201D and u201CCHANGING lc_local_value.u201D?
2. What is the role of the CALL FUNCTION 'CONVERT_TO_LOCAL_CURRENCY', in particular the Exporting and Importing parts?
3. Can I say that u201CCOMM_STRUCTURE-ORDER_VALu201D in the subroutine is passed to u201Clc_document_valueu201D in the u201CFORM loc_curr_convertu201D; and further passed to u201Cforeign_amountu201D in the u201CCALL FUNCTION 'CONVERT_TO_LOCAL_CURRENCY'u201D?
4. Finally, what becomes of my original u201CActual Goods receipt quantityu201D( 0GR_QTY ) which I am writing the routine for? I donu2019t see any where in the code that it is being referred to? Do any of these codes affect the value of 0GR_QTY?
5. Also, if there are 3 different subroutines in the INCLUDE and I am making the change described in #4 above, how do I know which of the 3 subroutines to call?
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So I am reviewing a transfer routine in for u201CActual Goods receipt quantityu201D and routine an INCLUDE statement: INCLUDE RS_BCT_MM_UPDATE_RULES.
The update rule also includes the following properties to run the following subroutine in the Include:
IF u2026..
perFORM LOC_CURR_CONVERT
           USING    COMM_STRUCTURE-ORDER_VAL
                    COMM_STRUCTURE-DOC_DATE
                    COMM_STRUCTURE-ORDER_CURR
                    COMM_STRUCTURE-LOC_CURRCY
                    COMM_STRUCTURE-EXCHG_RATE
           CHANGING RESULT.
I verified in the INCLUDE (RS_BCT_MM_UPDATE_RULES) and the subroutine is as follows:
FORM loc_curr_convert
  USING    lc_document_value
           lc_date
           lc_document_currency
           value(lc_local_currency)
           lc_rate
  CHANGING lc_local_value.
conversion of lc_rate from floating-point to decimal. Necessary for *
call of CONVERT_TO_LOCAL_CURRENCY.
data lc_rate_dec type p decimals 5.
lc_rate_dec = lc_rate.
  IF lc_document_currency = lc_local_currency
  no conversion necessary -> Main case 1
    AND NOT ( lc_document_currency IS INITIAL
           OR lc_local_currency IS INITIAL ) .
    lc_local_value = lc_document_value.
  ELSEIF NOT ( lc_document_currency IS INITIAL
  OR lc_local_currency IS INITIAL OR lc_date IS INITIAL ) .
  conversion necessary with lc_date -> Normally not possible
    CALL FUNCTION 'CONVERT_TO_LOCAL_CURRENCY'
      EXPORTING
        date                 = lc_date
        foreign_amount       = lc_document_value
        foreign_currency     = lc_document_currency
        local_currency       = lc_local_currency
        rate                 = lc_rate_dec
      IMPORTING
      EXCHANGE_RATE        =
        local_amount         = lc_local_value
      EXCEPTIONS
        NO_RATE_FOUND        = 1
        OVERFLOW             = 2
        NO_FACTORS_FOUND     = 3
        NO_SPREAD_FOUND      = 4
        DERIVED_2_TIMES      = 5.
    IF sy-subrc NE 0.
  message a802 with lc_date lc_document_currency lc_local_currency
                    sy-subrc.
    ENDIF.
  ELSE.
  if conversion not possible -> assign target values
    lc_local_value = lc_document_value.
    lc_local_currency = lc_document_currency.
  ENDIF.
ENDFORM.

Answer 1

HI,
Thanks so much the explanations.
I just verified again on our dev system and the update rule for 0GR_QTY (Actual goods receipt quantity) include the following:
    perFORM QUANTITY_CONVERT
       USING    COMM_STRUCTURE-CPQUAOU
                COMM_STRUCTURE-po_UNIT
                COMM_STRUCTURE-base_uom
                COMM_STRUCTURE-numerator
                COMM_STRUCTURE-denomintr
       CHANGING RESULT
Now, in the include, I also found:
FORM QUANTITY_CONVERT
  USING    QC_SOURCE_VALUE
           QC_SOURCE_UNIT
           VALUE(QC_TARGET_UNIT)
           QC_UMREZ
           QC_UMREN
  CHANGING QC_TARGET_VALUE.
i.  Does it mean it actually does quantity conversion?
ii. If you have access to the INCLUDE I will appreciate some hints on what the subroutine QUANTITY_CONVERT is doing. It does not appear do to be saying anything about quantity conversion; but it is supposed to be doing something with the parameters being passed from the update routine.
iii. In your response to #5, after all the computation in the INCLUDE, what comes back to the Update rule  i.e. what comes back to become the value of 0GR_QTY?
Is it the u201CRESULT.u201D in the update rule or u201CQC_TARGET_VALUE.u201D in the subroutine in the INCLUDE.
iv. So, am to create an Update rule for 0PSTNG_DATE and the source is BUDAT; and I need to write a routine using the include INCLUDE RS_BCT_MM_UPDATE_RULES.
I looked through the INCLUDE and identified all the subroutines in this INCLUDE as follows:
QUANTITY_CONVERT
LOC_CURR_CONVERT
GET_WEEK
WEEK_DAY
QUARTER_DAY
--Does it mean that to use this subroutine, I can only use the USING parameters of one of these listed subroutines?
--Also, does it mean that because 0PSTNG_DATE is a date, I can only use one of
GET_WEEK
WEEK_DAY
QUARTER_DAY
--Or, are there other includes to be used for 0PSTNG_DATE
Thanks