You can save the current layer settings in a drawing as a saved layer state and restore them later. Saving layer states is convenient if you need to return to particular settings for all layers during different stages in completing a drawing or for plotting.
For example, a facilities manager might save a layer state of individual floor plans and furniture, cable, and HVAC layouts to separate this information from a complete building layout.
Layer settings you can save and restore include layer states, such as on or locked, and layer properties, such as color or linetype. You can choose which layer states and layer properties you want to restore later.
You can modify the properties of a saved layer state. All layer properties other than the layer name can be edited. You can also add new layers to a layer state if new layers were added since the later state was saved.
When an xref containing saved layer states is inserted in the host drawing, the xref layer states are listed by name and can be viewed in the Layer States Manager. Although they can be restored, they cannot be edited. Xref layer states are identifiable because the layer state name is preceded by the xref drawing’s name and separated by a double underscore symbol. (Example: Xref Name__Layer State Name.) When the xref is bound to the host drawing, layer states are identifiable by $0$ that displays between the xref name and layer state name. (Example: Xref Name$0$Layer State Name.)
Layer states from nested xrefs are also included. Layer states from xrefs are removed from the host drawing when the xref is detached or unloaded.