A device-type's component structure is a hierarchical arrangement of component placeholders, each capable of being fulfilled by one or more component-types. Think of it like a car engine: A Toyota Corolla has an 'engine placeholder' that can accommodate different types of engines. In the same way, each component placeholder in device can be fulfilled by various component-types.

E.g. a device-type could have a component placeholder named IoT component which can be fulfilled by a Bluetooth IoT component or a combined Bluetooth LoRaWAN component.

Any physical device produced according to a particular device-type must fulfill the component structure’s contract by populating all mandatory component placeholders with compatible components (i.e. components of component-types that fit the component placeholder's definition), while optional placeholders may remain unfilled or be fitted with compatible components. During the device’s lifetime, when components are replaced or upgraded, the device must continue to adhere to the contract defined by the component structure.

Only regular device-types can define a component structure.