When the Debugger pauses, use the Expression Editor to evaluate expressions using mapping variables and ports in a selected transformation.
You can evaluate expressions in the following transformations:
Aggregator transformation
Expression transformation
Filter transformation
Rank transformation
Router transformation
Update Strategy transformation
When you create an expression, you use references to ports within the transformation. The Expression Editor does not display ports for other transformations in the mapping. When you evaluate the expression, the Debugger returns the result of the expression in a message box.