These levels refer to the extent of fire alarm coverage within a property: LD1 Coverage: Provides full protection with alarms installed in all rooms, including high-risk areas like kitchens and living rooms, as well as escape routes. LD2 Coverage: Alarms are installed in high-risk areas and escape routes, but not necessarily in every room. LD3 Coverage: The basic level of coverage, with alarms installed only in escape routes, such as hallways and staircases.