tokens: For each satellite platform subsystem and for each payload the SSUM shall provide the following for each unit : 1 . a detailed design description , including block diagrams , functional diagrams , logic and circuit diagrams ; 2 . physical characteristics including location and connections to the satellite structure , axes definition and alignment , dimensions and mass properties ; 3 . principle of operation and operational constraints of the unit or equipment . 4 . If a unit is composed of many complex elements or modules , it may be necessary to provide a lower level of breakdown .