We found the SAP Developer Network Wiki Posting by Noreen Armstrong here. We think this is something that isn’t easy to find so we are cross posting it for your information as well.
The creation of reports in XL Reporter (XLR) frequently requires information to be extracted from user defined fields (UDF) in the database. As XL Reporter does not automatically know which UDFs have been added to the database, they are not included by default. However, XLR provides the facility to access these UDFs.
For example, a customer that is also a supplier has 2 UDFs defined in the Business Partner (BP) Master Data. These UDFs exist at header level showing the counterpart BP and their respective balance. The financial accountant requires a report detailing how much each of these types of business partners (that are both customers and suppliers) actually owes the company. The accountant has requested that the existing report in XLR showing the customer name, the supplier name and their respective balances should also show the total balance due to/owed by these clients.
In the following example, customer ‘C23900′ is also a supplier (BP code = V60000). The BP Master Data record for customer ‘C23900′ shows ‘V6000′ in the UDF ‘Counterpart BP’ and this supplier’s current balance in the UDF ‘Counter BP Balance’.

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