NBN ISO/IEC/IEEE 32430:2022

This standard defines a method for the sizing of non-functional software requirements. It complements ISO/
IEC 20926:2009, which defines a method for the sizing of functional user requirements (FUR).1
This standard also describes the complementarity of functional and non-functional sizes, so that sizing both
functional and non-functional requirements (NFR) do not overlap. It also describes how non-functional size,
together with functional size, should be used for measuring the performance of software projects, setting
benchmarks, and estimating the cost and duration of software projects.
In general, there are many types of non-functional software requirements. Moreover, non-functional aspects
evolve over time and may include additional aspects in the as technology advances. This standard does not
intend to define the type of NFR for a given context. Users may choose ISO 25010:2011 or any other standard
for the definition of NFR. It is assumed that users will size the NFR based on the definitions they use.
This standard covers a subset of non-functional types. It is expected that, with time, the state of the art can
improve and that potential future versions of this standard can define an extended coverage. The ultimate
goal is a version that, together with ISO/ IEC 20926:2009, covers every aspect that may be required of any
prospective piece of software, including aspects such as process and project directives that are hard or
impossible to trace to the software' s algorithm or data. The combination of functional and non-functional size
would then correspond to the total size necessary to bring the software into existence.
Calculating the effort and duration of the implementation of the NFR is outside the scope of this standard.