The requirement specification (also requirement specification , requirement catalog , product sketch , customer specification or user specification ) describes the entirety of the customer's requirements for the deliveries and services of a contractor .
The requirements in a specification should be formulated as general as possible and as restrictive as necessary. This gives the contractor the opportunity to work out a suitable solution (e.g. software) without being restricted in his solution competence by overly specific requirements.
The client can use the specification sheet in a tender and send it to several possible contractors. They each create a specification sheet , which describes in more concrete form how they intend to solve the requirements in the specification sheet. The client then selects the most suitable for him from the suggestions of the possible contractors.
According to DIN 69901-5 (terms of project management), the specification describes the "totality of the demands on the deliveries and services of a contractor within an order specified by the client". Within the framework of a contract for work or a contract for work and services and the associated formal acceptance , the specification sheet precisely describes the verifiable services and deliveries .
The specification sheet usually describes what and what something should be done. The primary addressees of the specifications are the contractors . In addition, other addressees are the (external or internal) client as the approver of the specification sheet, as well as project managers, requestors and other stakeholders as (project) participants.
A specification is often written in text form. Details and specifications are made, for example, using tables, drawings, graphics or modeling languages .
A specification can be structured in different ways. The following information is typically taken into account:
- Description of the current state
- Description of the target concept
- Description of interfaces
- Functional requirements
- Nonfunctional requirements
- Risk acceptance
- Sketch of the development cycle and the system architecture
- scope of delivery
- Acceptance criteria
Often a clarification phase follows the creation of the specification sheet. In it, the requirements are discussed with the (possible) contractor, analyzed for contradictions with regard to implementation and, if necessary, detailed.
In the next step, the (possible) contractor creates the specification that describes how and with what something should be implemented. According to DIN 69901-5, the specification contains the "implementation specifications drawn up by the contractor based on the implementation of the specifications specified by the client". Each requirement of the specification can usually be assigned one or more services in the specification. Particularly in the software area (for example in ERP systems ), requirement specifications are often created as a table with fields, in which the software provider evaluates each item listed, whether it can meet it in the standard or not.
So the order of the two documents in the development process is clear: The requirements (requirements) are services (features) met. In combination with the offer, this often represents the contractual basis of the services to be performed.
Depending on the area of application and the industry, specification sheets can differ greatly in structure and content. In practice, the terms requirement specification, functional specification, service description and specification are often not clearly delimited from one another or even used synonymously. The fuzzy use of the terms and the lack of separation of what and what for, how and with what causes misunderstandings.
Compared to a technical concept , a specification sheet is enriched with formal aspects that are necessary for a tender.
The criteria of a specification sheet are generally not applicable to a sales contract according to § 433 BGB or a legally equivalent delivery contract, since the deliveries in the sales contract are determined by a specification unilaterally specified by the supplier and by the delivery quantity unilaterally specified by the customer .
In some industries, standardized specifications for specifications and their processing have become established.
In software engineering , a requirement specification is a possible result of a requirements analysis and thus a part of requirements management . The IEEE Standard Software Requirements Specification is often used, a document that summarizes the functional specification and the requirement specification .
In the international space specifications used orient themselves often at the NASA standard, to facilitate international cooperation. The following principle has emerged:
- The client creates a requirements specification (spec requirements) that contains the mission requirements and conditions (for example, it is a manned laboratory module for. ISS delivered that with the space shuttle to be transported there);
- The contractor replies with an implementation specification (design-to-spec) which specifies the design chosen by the contractor (e.g. a cylindrical printing module with a specific diameter and length);
- The client formally accepts the more detailed implementation specification. However, in the event of a later conflict, the requirements specification takes precedence.
Furthermore, the client demands in a specification / statement of work (SOW) how and with what means the product to be delivered according to the requirements specification is to be developed, manufactured and verified (development logic, checks / reviews, documents to be delivered, etc.). The contractor replies with various plans (design and development plan, production plan, EMC control plan, etc.) that describe the implementation of the SOW in detail (e.g. who writes the minutes of a meeting and in what time frame the parties involved must agree) .
Norms and standards
- DIN 69901-5: Project management - Project management systems - Part 5: Terms
- VDI 2519 sheet 1: Procedure for the creation of requirement specifications
- VDI 2519 Sheet 2: Specification / functional specification for the use of conveyor and storage systems
- VDI 3694: Requirement specification / functional specification for the use of automation systems
- VDI 4403 Sheet 1: Modernization and expansion of conveyor systems and logistical systems during ongoing operations
- IEEE 830-1998: Software Requirements Specification , requirement specifications for software systems
- Section of the German Society for Project Management eV (GPM) on DIN 69901.
- Axel Naumann: Business Analysis . Giessen 2018, p. 325
- Axel Naumann: Business Analysis . Giessen 2018, p. 330
- Columbus Design Spec (COL-RIBER-SPE-0028, iss 10 / F, June 25, 2004).
- Axel Naumann: Business Analysis - Systematic Requirements Management for User-Oriented Solutions . Giessen 2018, ISBN 978-3-945997-11-6 .
- Maik Pfingsten: Successfully writing specifications . 2nd Edition. Norderstedt 2016, ISBN 978-3-7392-4911-7 .