To create groups of entities from existing groups of superior dimensions, in the Mesh menu select Group of underlying entities.
The following dialog box will appear:
In this dialog box specify the name of the resulting group, types of entities and set of source groups.
In the figure below, there are two source Volume groups:
In this case the following results for Faces, Edges and Nodes are obtained:
See Also a sample TUI Script of a Creating groups of entities from existing groups of superior dimensions operation.