Displaying Key Information for Business Objects 
Use
The Key of a BAPI is a field or a set of fields which together identify a unique record in the R/3 table. For example, the key fields for the GeneralLedgerAccount business object are the COMPANYCODE and the GLACCT, which is the G/L account number.
This procedure describes how to get a list of the key field(s) of a business object.
Procedure
Once the Properties pane opens, you only need to click on a key name to view its details in the Properties pane.