From the URS a variety of input requirement documents may be generated. Typical input requirements fall into three categories.
Functional Requirements
The first category is the functional requirements (FRS), which specify what the device does including its’ operational characteristics, inputs and outputs.
Performance Requirements
The second category is the performance requirements which specify the characterization of during use. These may include operational environmental ranges, ranges of quantitation, accuracy, precision and other performance characteristics.
Interface Requirements
Finally, any interface requirements should be specified. Interface requirements may be external or internal, but the specifics of any interface should be included. External interfaces may be patient/product interfaces, or operator/product, or may be external communication interfaces. Internal interfaces may be software/hardware or communication interfaces. Each interface needs to be addressed, to ensure the system works together. The documentation here varies by the organization and product.
FRS, DIR, MRS, ERS
There is almost always an functional requirement specification (FRS) or sometimes specifically a Design Input Requirements (DIR) document. Sometimes there are additional documents created to capture specifics of the device. For example, a mechanical requirement specification (MRS) or electrical requirement specification (ERS) may be generated as independent documents or may be sections within the FRS, or DIR. In addition, there may be specific safety requirements, and regulatory requirements that need to be considered, and of course applicable outputs of risk management may also introduce several requirements.