National Aeronautics and Space Administration (NASA). This Technical Standard approved by NASA December 1998. 77 p. This technical standard for reliability and maintainability (R&M) provides guidance to customers (or purchasers) and suppliers (or contractors) on R&M requirements development, design implementation, and evaluation. It has been developed to provide a centralized source of information for establishing R&M performance-based requirements, design factors, and metrics for use on all new NASA programs/projects and contracts. It addresses the challenge of managing mission risk in the development and operation of cost and time constrained flight programs/projects and other NASA assets.