This part of ISO/IEC 15026 uses and elaborates on the concept of integrity levels with corresponding integrity level requirements that are required to be met in order to show the achievement of the integrity level. It places requirements and offers recommendations on the methods for defining and using integrity levels and their integrity level requirements. It covers systems, software products, and their elements as well as relevant external dependences. This part of ISO/IEC 15026 is applicable to systems and software and is intended for use by: a) Definers of integrity levels such as industry and professional organizations, standards organizations, and government agencies. b) Users of integrity levels such as developers and maintainers, suppliers and acquirers, users, and assessors of systems or software and for the administrative and technical support of systems and/or software products. The definitions of integrity levels are specified by the first and used by the second. One important use is their use by suppliers and acquirers as part of their agreements, for example to aid in assuring safety characteristics of a delivered system or product. This part of ISO/IEC 15026 does not prescribe a specific set of integrity levels or their integrity level requirements. In addition, it does not prescribe the way in which integrity level use is integrated with the overall system (or software) engineering life cycle processes.