1.1 This International Standard – defines RAMS in terms of reliability, availability, maintainability and safety and their interaction; – defines a process, based on the system life cycle and tasks within it, for managing RAMS; – enables conflicts between RAMS elements to be controlled and managed effectively; – defines a systematic process for specifying requirements for RAMS and demonstrating that these requirements are achieved; – addresses railway specifics; – does not define RAMS targets, quantities, requirements or solutions for specific railway applications; – does not specify requirements for ensuring system security; – does not define rules or processes pertaining to the certification of railway products against the requirements of this standard; – does not define an approval process by the safety regulatory authority. 1.2 This International Standard is applicable – to the specification and demonstration of RAMS for all railway applications and at all levels of such an application, as appropriate, from complete railway routes to major systems within a railway route, and to individual and combined sub-systems and components within these major systems, including those containing software; in particular • to new systems, • to new systems integrated into existing systems in operation prior to the creation of this standard, although it is not generally applicable to other aspects of the existing system, • to modifications of existing systems in operation prior to the creation of this standard; although it is not generally applicable to other aspects of the existing system; − at all relevant phases of the life cycle of an application; − for use by Railway Authorities and railway support industry. NOTE Guidance on the applicability is given in the requirements of this standard.