Icon with dosing or dispenser funnel symbol and door and compound or raw materials symbol showing stacked/grouped particles and null symbol or crossed circle. Used in material dosing, dispensing control systems and precision measurement applications. Indicates access control, door closure, or alternate barrier system. Used in compound processing, raw materials, quality control, material handling systems and chemical mixture monitoring interfaces. Indicates empty values, null states, missing content, absence of data, initialization state, or undefined parameters Used in batch processing control, monitoring systems and production line management interfaces.