This part of ISO/IEC TR 15504 defines a reference model for software processes and process capability that forms the basis for software process assessment. The reference model defines at a high level the fundamental objectives that are essential to good software engineering. The high-level objectives describe what is to be achieved, not how to achieve them. This reference model is applicable to any software organization wishing to establish and subsequently improve its capabilities in the acquisition, supply, development, operation, evolution and support of software. The model does not presume particular organizational structures, management philosophies, software life cycle models, software technologies, or development methodologies. The architecture of this reference model organizes the processes to help software personnel understand and use them for continuous improvement of the management of software processes. For software process assessment, an assessor uses a more detailed model(s) compatible with this reference model, containing a comprehensive set of indicators of process performance and process capability, to make judgments about the capability of the organization's processes. This part of ISO/IEC TR 15504 specifies the requirements to be met in order for a model(s) to be compatible with the reference model. ISO/IEC TR 15504 is not intended to be used in any scheme for the certification / registration of the process capability of an organization. Table 1 shows the main audiences for this part of ISO/IEC TR 15504, why each group needs the reference model, and how and when it will be used.NOTE Copyright release for the Reference Model: Users of this part of ISO/IEC TR 15504 may freely reproduce the detailed descriptions contained in the reference model as part of any Assessment Model based upon the reference model, or as part of any demonstration of compatibility with this reference model, so that it can be used for its intended purpose.