A requirement specification is a document in which the requirements for a project, software, system or device are defined. It contains all project-specific requirement specifications. Requirements specifications and their structuring are described in DIN 69901-5 and are defined as "the totality of the requirements for the deliveries and services of a contractor within an order, specified by the customer".
Specifications are structured depending on the project, but should contain certain points. Thus, the initial situation and the objective. The former should show the actual situation and the current realization. The objective should describe the target state at the end of the project and what expectations are associated with it. Other important points are the functional and non-functional requirements. These are the functions that the project must fulfill upon completion, and for the non-functional requirements, efficiency, security, reliability, extensibility, and maintainability.
The requirements specification should also show the scope of delivery and the project planning with the project phases and the subprojects. In addition, the quality assessment and the acceptance conditions.