Data Transformation Engine Type Designer Reference Guide

Chapter 1 - Introduction Hierarchy of a Type Tree
For example, the My Tree.mtt type tree does not allow you to see Field as a
component of Record, or Record as a component of File. By looking at a type
tree in the type tree window, you cannot see how the data is defined because
composition of the data is not visible. To view the data composition, double-click
the group type File in the tree to open the File ROOT group window.
To view the components of Record, click the plus sign to expand the group type.