本标准定义了一种确定非功能性软件需求大小的方法。它补充了ISO/IEC 20926:2009，该标准定义了功能用户需求（FUR）的规模确定方法。本标准还描述了功能性和非功能性尺寸的互补性，以便功能性和非功能性需求（NFR）的尺寸不重叠。它还描述了如何使用非功能性规模和功能性规模来衡量软件项目的性能、设置基准，以及估计软件项目的成本和持续时间。一般来说，有许多类型的非功能性软件需求。 此外，非功能方面会随着时间的推移而演变，并且随着技术的进步，可能会包括其他方面。本标准不打算定义给定环境下的NFR类型。用户可以选择ISO 25010:2011或任何其他标准来定义NFR。假设用户将根据他们使用的定义来确定NFR的大小。本标准涵盖了非功能类型的子集。预计随着时间的推移，最新技术水平将有所提高，本标准的潜在未来版本将定义更广泛的覆盖范围。最终目标是一个版本，与ISO/IEC 20926:2009一起，涵盖任何潜在软件可能需要的每个方面，包括难以或不可能追溯到软件算法或数据的过程和项目指令等方面。 然后，功能性和非功能性大小的组合将对应于使软件存在所需的总大小。计算NFR实施的工作量和持续时间不在本标准的范围内。

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). 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.