When you select an object from the viewport, your selection includes all the entities of lower dimensionality that are associated with the object. For example, if you select a cell, your selection includes all the faces, edges, and vertices associated with the cell. Similarly, if you select an edge, your selection includes all the vertices associated with the edge. In some circumstances you may want to exclude the entities of lower dimensionality from your selection. For example, if you select an edge to include in a set, you may not want the set to contain the vertices at each end of the edge. Excluding entities of lower dimensionality from your selection may solve any problems that you encounter with overconstraints.
To exclude objects from your selection:
Select all the objects using a combination of select, drag-select, [Ctrl]+Click, and [Shift]+Click.
ABAQUS/CAE highlights the selected objects in red.
[Ctrl]+Click an object to exclude it from your selection.
ABAQUS/CAE highlights the excluded objects in purple.