IEC 61703:2016提供了IEC 60050-192:2015中定义的选定可靠性、可用性、可维护性和维护支持措施的数学表达式。此外，它还介绍了一些IEC 60050-192:2015中未涉及的术语。它们与项目类别系统的各个方面相关（见下文）。根据IEC 60050-192:20 15，可靠性【192-01-22】是项目在需要时执行的能力，项目【192-01-01】可以是单独的零件、组件、设备、功能单元、设备、子系统或系统。为了考虑数学限制，本标准将项目分为作为一个整体考虑的单个项目（例如单个组件）和由几个单个项目组成的系统。它为系统和单个项目的数学表达式提供了一般考虑，但是更容易建模的单个项目根据其修复方面进行了更详细的分析。本标准主要适用于硬件可靠性，但许多术语及其定义可能适用于包含软件的项目。这第二版取消并取代了2001年出版的第一版。本版构成技术修订版。与上一版相比，此版本包括以下重大技术变更: -尽可能自包含的标准； -单个项目和系统之间的项目拆分； -概括由几个部件组成的系统的可靠性概念[引入条件失效强度(Vesely失效率)； -介绍状态转移和马尔可夫模型； -将可用性推广到生产可用性]； -引入曲线以说明各种概念。 关键词:可靠性的数学表达式

IEC 61703:2016 provides mathematical expressions for selected reliability, availability, maintainability and maintenance support measures defined in IEC 60050-192:2015. In addition, it introduces some terms not covered in IEC 60050-192:2015. They are related to aspects of the system of item classes (see hereafter). According to IEC 60050-192:2015, dependability [192-01-22] is the ability of an item to perform as and when required and an item [192-01-01] can be an individual part, component, device, functional unit, equipment, subsystem, or system. To account for mathematical constraints, this standard splits the items between the individual items considered as a whole (e.g. individual components) and the systems made of several individual items. It provides general considerations for the mathematical expressions for systems as well as individual items but the individual items which are easier to model are analysed in more detail with regards to their repair aspects. This standard is mainly applicable to hardware dependability, but many terms and their definitions may be applied to items containing software. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- standard made as self containing as possible;
- item split between individual items and systems;
- generalization of the dependability concepts for systems made of several components [introduction of the conditional failure intensity (Vesely failure rate);
- introduction of the state-transition and the Markovian models;
- generalization of the availability to production availability];
- introduction of curves to illustrate the various concepts. Keywords: mathematical expressions for dependability