Design inputs include customer needs as well as customer requirements. These are the aspects of the product that are expected to happen. For example, if you state that your product has a sensor that should flash red when interacting with a certain indicator, it should not flash green. These are the broader inputs that are addressed in the DID. The DSD document contains the more specific aspects of the product. Going back to that example, the measurements for the sensor, as well as the intensity of the green light should be stated along with a tolerance. Ultimately, the design inputs are what is expected to happen with the product with specific requirements.