When the lspec (``S'') button is in the down position, Xic is placed in layer-specific mode for selections.
In layer-specific mode, only objects on the current layer, or subcells containing objects on the current layer, can be selected and deselected with mouse operations. Otherwise, any visible object can be be selected or deselected. Instances are selected during a layer-specific point select if there is no other qualifying geometry where the user clicked, and only instances that contain objects on the current layer can be selected in layer-specific mode. The layer-specific mode affects many of the commands and operations in Xic, typically limiting the operation to objects on the current layer when active.
Layer-specific mode is indicated by a small box icon in the far right side of the layer table. Clicking on this icon with button 1 will also toggle layer-specific mode on and off.
Layer-specific mode can also be set from the Layer Specific button which appears in the Selection Control Panel, which is brought up by the layer (``C'') button in the Selection Control button group.