ISO/IEC 33004:2015规定了过程参考模型、过程评估模型和成熟度模型的要求。本国际标准中定义的要求形成了一个结构，规定 a） 与过程评估绩效相关的过程模型类别之间的关系， b） 过程参考模型和过程性能的规定性/规范性模型之间的关系，例如由ISO/IEC 12207和ISO/IEC 15288中定义的活动和任务构成， c） 整合过程参考模型和过程度量框架，以建立过程评估模型， d） 在过程评估模型中使用过程绩效和过程质量的通用评估指标集，以及 e） 成熟度模型和过程评估模型之间的关系，以及使用不同过程评估模型中的元素构建成熟度模型的程度。

ISO/IEC 33004:2015 sets out the requirements for process reference models, process assessment models, and maturity models. The requirements defined in this International Standard form a structure which specifies a) the relationship between the classes of process model associated with the performance of process assessment, b) the relationship between process reference models and prescriptive/normative models of process performance, as constituted by, for example, the activities and tasks defined in ISO/IEC 12207 and ISO/IEC 15288, c) the integration of process reference models and process measurement frameworks to establish process assessment models, d) the use of common sets of assessment indicators of process performance and process quality in process assessment models, and e) the relationship between maturity models and process assessment models and the extent to which a maturity model can be constructed using elements from different process assessment models.