Is Dynamic Layer
This indicates that the current Layer of a Component Gauge is Dynamic, which means it can be swapped with other Layers based on the aircraft in use.
Layer Replaces
Once a Layer has been enabled as Dynamic, it will appear in this list. Selecting the Layer in the list indicates that the it replaces the Layer currently shown on the Canvas.
Used By
Tick the checkboxes for all aircraft that will use the Layer replacement.