What is a requirements catalogue, which contents are described in it and what is the difference to the requirements list?
A part of the customer requirements specification
A requirements catalogue is a list of requirements through which a desired project goal is to be achieved. Ideally, it should be a structured and prioritised list of requirements for a software or system. The requirements should be clearly defined, complete and comprehensible, atomic, identifiable, uniformly documented, verifiable and consistent.
Often the terms requirement catalogue and requirement specification / customer requirement specification are used synonymously, but it would be more correct to understand the requirement catalogue as input for the requirement specification / customer requirement specification. In the course of the demand analysis it is determined which features a software to be developed or a system to be developed must provide. This catalogue flows into the requirement specification, which covers beyond that the basic conditions within the development or the project. It is the basis for the realisation by a contractor. Based on this, the contractor formulates a software or system requirement specification and thus the plan for the implementation of the requirements. The specifications form the basis for the conclusion of the contract between the client and the contractor.
Requirements catalogue and requirements list
In addition to the synonymous use of requirement catalogues and customer requirement specifications, the list of requirements is often used in practice with the same meaning. If both the catalog and the list present requirements in a structured way, what is the difference between the two terms?
Often the list of requirements is provided only at the beginning of the development activity – on basis of the software or system requirement specification. The requirements list thus becomes a tool for searching for solutions and for detailing and evaluating possible concepts. At least theoretically it could become – in addition to the software or system requirement specification – a part of the contract between client and contractor.
Contents of the requirements catalogue
There are several recommendations on how a catalogue of requirements should be structured. For example
- functional requirements and non-functional requirements such as usability, reliability, changeability, etc.,
- interface requirements and interoperability requirements,
- maintenance and documentation requirements,
- and safety requirements
can be described. Whether general conditions such as the operational environment and the system context are already documented in the catalogue of requirements or “first” in the customer requirements specification is secondary in itself. The actual concept and also the target concept, the system architecture and the acceptance criteria are usually recorded in the customer requirements specification.
With regard to the prioritization of requirements in the requirements catalog, there are various options such as the MoSCoW method, the pairwise comparison of requirements, or the use of clear and unique priorities.