The design prepared in the planning stage of a project and submitted as part of the project brief. The drawings and specification s that comprise the Preliminary Design should be clearly specified as a matter of policy and provide the basis for the Appropriation estimate. [D01243] CCCP
Preliminary Design (the second of the Acquisition Phase activities) converts the functional baseline from Conceptual Design (the ‘what' of the system) into a preliminary definition of the system physical architecture (the ‘how').
(IEEE) (1) The process of analyzing design alternatives and defining the architecture, components, interfaces, and timing and sizing estimates for a system or component. See: detailed design. (2) The result of the process in (1).