Workflow Question

[Carson, Wayne]

Example #1.
I am looking at object type: BUS2081.  Within that object type, there is a
method DISPLAY.  Here is the program code:
 
SET PARAMETER ID 'RBN' FIELD object-key-invoicedocnumber.
SET PARAMETER ID 'GJR' FIELD object-key-fiscalyear.
CALL TRANSACTION 'MR3M' AND SKIP FIRST SCREEN.
 
I created a standard task with the method and a template that uses the
standard task.  I set a breakpoint in the code at the CALL Transaction
statement.  The key fields for this object type are:
 
IncomingInvoice.InvoiceDocNumber
IncomingInvoice.FiscalYear
 
The binding created a field &INCOMINGINVOICE& and it gets moved
_WI_OBJECT_ID.
 
The values for object-key-invoicedocnumber and object-key-fiscalyear are
both empty.
 
I used transacton SWUE and populated both the invoice document number and
fiscal year.
 
Example #2.
 
When I created my own OBJECT TYPE and METHOD DISPLAY, I used the following
coding in my program.  This coding worked.  wk_belnr and wk_gjahr both have
values.  Of course in my workflow template, I had to specify these as IMPORT
PARAMETERS.
 
data: wk_belnr like rbkp-belnr,
 wk_gjahr like rbkp-gjahr.
 
  swc_get_element container
     'Invoice' wk_belnr.
 
  swc_get_element container
     'FiscalYr' wk_gjahr.
 
  SET PARAMETER ID 'RBN' FIELD wk_belnr.
  SET PARAMETER ID 'GJR' FIELD wk_gjahr.
  CALL TRANSACTION 'MR3M' AND SKIP FIRST SCREEN.
 
Here is my question: How does SAP know to move the data from the EVENT
container to the WORKFLOW container in Example #2.  I used my own field
names.  How does SAP perform the mapping?  This is code we don't see
anywhere.
 
Why didn't Example #1 work?  What is missing?
 
Thank you,
 
Wayne Carson