The Floors panel allows you configure ranges of Z positions that represent a floor in order to make multifloor models more manageable.
The following properties are on the Floors panel:
The top "eye" button will show/hide all objects on all floors. The other eye buttons will show/hide all objects on the corresponding floor.
No Select Floors
The top "lock" button will toggle the No Select flag of all objects on all floors. The other lock buttons will toggle the No Select flag of all objects on the corresponding floor.
Adds another floor.
Defines the bottom Z position of the current floor. This floor will contain all object between this Z position and the Z position of the floor above it.
Set Grid Z
Sets the view's Grid Z to the Floor Z of the corresponding floor.
Removes the corresponding floor.