Unreconciled layers are new layers that have been added to the drawing and have not yet been acknowledged by the user and manually marked as reconciled.
Reconciling new layers is the process of manually reviewing new layers so that you can avoid potential errors before plotting your drawing or when restoring a layer state.
Unreconciled layers are new layers that have been added to the drawing or to attached xrefs since the layer list was last evaluated. The layer list is checked for new layers when a command, such as PLOT is used. In new drawings, the layer baseline is created when the drawing is saved or plotted for the first time. When a new drawing is first saved, the layer baseline is created, and all layers present in the saved drawing are considered reconciled (not new). Layers that are added after a drawing is first saved are considered new unreconciled layers.
When a command that is set in the Layer Settings dialog box or LAYEREVAL system variable is used, the layer list is checked at that time and compared to the baseline. If there are new layers, notification will display and the Unreconciled New Layers filter is automatically created and activated in the Layer Properties Manager.
Unreconciled layers become reconciled by right-clicking the layer and clicking the Reconcile Layer option. Once a layer has become reconciled, it is removed from the Unreconciled New Layers filter. After all new layers are reconciled, the Unreconciled New Layers filter is removed.