ECSS-E-20A, SPACE ENGINEERING ELECTRICAL AND ELECTRONIC (4 OCT 1999)., This Standard establishes the basic rules and general principles applicable to the electrical, electronic, electromagnetic, microwave and optical engineering processes. It specifies the tasks of these engineering processes and the basic performance and design requirements in each discipline. It defines the terminology for the activities within these areas. It defines the specific requirements for electrical subsystems and payloads, derivingfrom the system engineering requirements laid out in the Space System Engineering Standard ECSS-E-10.