Data Transformation Engine Design Studio Tutorial

Chapter 11 - Partitioning Types to Simplify Map Rules Viewing Component Numbers
Design Studio Tutorial
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Viewing Component Numbers
By default, component numbers do not display in the group window in the Type
Designer. When the Show component number option is enabled, a sequential
component number displays in the group window. This component number is
especially useful for viewing nested components. Use the Tools > Options dialog
box to configure the display of the group window.
In the Distributor Forecast Record Data group window, the Distributor
Partner group is component 1. The ApplicationID Field item type is component
2, Quantity Field is component 3, and so on.