4.2.7  Other Documentation  5  OSA Development Process  5.1  OSED Development Process  5.1.2  Describe the Physical and Functional Characteristics of the Solution’s Concept  5.1.1  Define the Boundaries  Documentation relating to existing design, tests, field performance, NAS operations research,  and detailed support (perhaps including recent SRM documents or portfolio SRM documents)  may already exist for the replacement, removal, or reconfiguration of existing NAS systems;  these may apply substantially to the new proposed action. The PO should consider conducting  an audit for applicable and reusable baseline documents and SRM documents that can form a  sound basis for legacy architecture, requirements, design, performance, and known NAS  constraints.  The OSED captures elements that comprise a CNS/ATM system (e.g., aircraft equipage, air  traffic service provider technical systems, communication service provider systems, and  procedural requirements), and it includes the operational performance expectations, functions,  and selected technologies of the CNS/ATM system. The OSED facilitates the formulation of  technical and procedural requirements based on operational expectations and needs.  Figure C.2 gives a logical overview of the steps required to conduct an OSED. Some of the  steps may overlap or be iterative in nature.  The required tasks for preparing an OSED are described in  Section 5.1.1 through Section 5.1.4.  Define the boundaries of the solution under consideration, including anticipated interfaces, a  technology’s independent layers, and common services among NAS systems and sub-systems  (both internal and external). Determine, separate, and document which elements of the solution  to describe and analyze for hazard identification. Identify shared resources (if any) for which  independent SRM was already performed.  Using models such as those described in the SMS Manual (e.g., the 5M Model), describe:  • The concept’s state by including physical and functional characteristics, • The environment’s physical and functional characteristics, • Air traffic services to be provided, C_SRMGSA_202003  Originally published March 2020  Uncontrolled copy when downloaded  C-8 Step 1 Define the boundaries Step 2 Describe the  capability’s physical/ functional  characteristics Step 3 Determine and list  the solution functions Step 4 Develop and  document the OSED Figure C.2: OSED High-Level Process 