When you select a mapplet that contains an Output transformation to use in a Mapplet transformation, the mapplet output fields appear on the Output Fields tab of the Properties panel.
The Mapping Designer displays the name, type, precision, scale, and origin for each output field in each output group. You cannot edit the transformation output fields. If you want to exclude output fields from the data flow or rename output fields before you pass them to a downstream transformation, configure the field rules in the downstream transformation.