For each struct element that you selected to flatten, the mapping contains a new Expression transformation

Extract_<element_of_struct_type>

with the following ports:

The complex port from which you want to extract elements.
One or more output ports for the extracted elements.
The output ports contain expressions that use complex operators to extract elements.
A dynamic port with ports from the upstream transformation

For each array element that you selected to flatten, the mapping contains a new Normalizer transformation

Flatten_<element_of_array_type>

with an input group and an output group. The output group contains the flattened normalized fields for the array element.

A final Expression transformation

Final_Flatten_Result

with a dynamic port that contains the flattened ports for the complex port and other ports in the upstream transformation.