IEC 61666:2010+A1:2021建立了系统内物体终端识别的一般原则，适用于所有技术领域（例如机械工程、电气工程、建筑工程、工艺工程）。它们可以用于基于不同技术的系统，也可以用于组合多种技术的系统。第二版取消并取代了1997年出版的IEC 61666第一版，构成了技术修订。与上一版相比，它包括以下实质性变化: -出版物中使用的术语已经适应于IEC 81346-1第2版中使用的术语； -提供了对指定原理的更全面的描述； -提供了示出与功能方面和位置方面相关的终端指定的附加示例；-提供了说明终端指定集的使用的附加示例； -以前的信息性附件A已成为标准中的一个条款。 根据IEC指南108，IEC 61666:2010具有水平标准的地位。

IEC 61666:2010+A1:2021 establishes general principles for the identification of terminals of objects within a system, applicable to all technical areas (for example mechanical engineering, electrical engineering, construction engineering, process engineering). They can be used for systems based on different technologies or for systems combining several technologies. This second edition cancels and replaces the first edition of IEC 61666 published in 1997 and edition constitutes a technical revision. It includes the following substantial changes with respect to the previous edition:
- the terminology used in the publication has been adapted to the one used in IEC 81346-1 Ed. 2;
- a more comprehensive description of the designation principles is provided;
- additional examples illustrating terminal designations related to the function aspect and location aspect are provided;
- an additional example illustrating the use of terminal designation sets is provided;
- the former informative Annex A has been turned into a clause in the standard.
IEC 61666:2010 has the status of a horizontal standard in accordance with IEC Guide 108.