This standard specifies the system engineering implementation requirements for space systems and space products development.Specific objectives of this standard are:-to implement the system engineering requirements to establish a firm technical basis and to minimize technical risk and cost for space systems and space products development;-to specify the essential system engineering tasks, their objectives and outputs;-to implement integration and control of engineering disciplines and lower level system engineering work;-to implement the "customer-system-supplier mode" through the development of systems and products for space applications.Depending of the product category, the application of this standard needs to be checked and if needed tailored. The pre-tailoring table in clause 7 contains the applicability of the requirements of this document and its annexes according to product type. Specific requirements related to system engineering, like technical specification, verification, and testing are specified in dedicated documents and standards within the set of ECSS system engineering standards ECSS-E-ST-10-XX.Discipline or element specific engineering implementation requirements are covered in dedicated ECSS standards. These standards are based on the same principles, process and documentation model. The applicability of each these standards can therefore not be considered in isolation from the others.NOTE 1The term "Discipline" is defined in ECSS-M-ST-10, as "a specific area of expertise within a general subject". The name of the discipline normally indicates the type of expertise, e.g. in the ECSS system mechanical engineering, software and communications are disciplines within the engineering domain.NOTE 2The requirements on the system engineering process are gathered in this standard; specific aspects of the SE process are further elaborated in dedicated standards. For engineering process both for SW and for Ground Segment and Operations the following standards are considered fully sufficient for development of these items:-ECSS-E-ST-70 Space engineering - Ground systems and operations-ECSS-E-ST-40 Space engineering - Software-ECSS-Q-ST-80 Space product assurance - Software product assuranceThis standard may be tailored for the specific characteristic and constrains of a space project in conformance with ECSS-S-ST-00.