This panel is called from the Panel bar by the following tool
If you do not see this tool, right-click in an empty area of the Panel bar and select it.
The same icon is available in the 3D toolbar that appears when you hover over an activated 3D object.
The Model Tree panel lets you see and work with the structure of a 3D object by showing the element hierarchy (nodes, groups, individual objects).
Right-click a member of the hierarchy for viewing and export commands.
Click the Options button at the top of the Model Tree panel to specify display options, color settings, render mode, or to export the whole tree into an XML file.
XML files are ideal for data distribution because they are easy to port and their display can be specified through style sheets.