Effective in version 10.0, you can configure mapping outputs. A mapping output is a single value that is the result of aggregating a field or expression from each row that the mapping processes. For example, a mapping output can summarize the total amount of an order field from all the source rows that the transformation receives. A mapping output expression is a field value or an expression to aggregate from the rows that the Expression transformation receives. You must define a mapping output in the mapping
view, before you can create the corresponding expression in the Expression transformation.