Form: Selection List
In SAP2000, click on objects with the left mouse button to select them, or with the right mouse button to view information about them (see Area Information Form, Line Information Form, Link Information Form, Point Information Form and Solid Information Form for examples of the forms displayed when an object is "right clicked").
If multiple objects lie one on top of the other, the Selection List form appears when the objects are selected by left clicking. When the Selection List form appears, highlight the name(s) of the object(s) in the list to be selected. Use the Ctrl key while highlighting to pick multiple names.
See the topics in the Select book of this Help for information on the various selection options available in SAP2000.