The Select menu provides shortcuts for selecting objects. All objects can be selected or None. Those currently not selected can be selected in place of those that are selected (Invert). For any selected objects you can cause those objects directly connected to them to also be selected (Connected). Doing this repetitively results in all connected objects being selected, which is the same as selecting Transitive. Finally, you can select all objects that are of the same type as the currently selected object.

Selecting same type actually works even if objects of different types are selected.

The following five check buttons modify how new objects are selected. Usually a new selection replaces the old selection as the final set of selected objects. With Union the final set of selected objects consists of the previously selected object plus the newly selected objects. Intersection results in those object that were previously selected and now selected again to be in the final selection, but no others. Remove removes from the old set of selected objects those that are newly selected. And Invert causes those objects newly selected to have their state of selection inverted--that is, those previously selected and now newly selected be no longer be selected, and those not previously selected but included in the new selection will become selected.