ISO/IEC 11573:1994标准是为了解决在PISN中进行的通信同步问题而制定的。PISN是一种专用的通信网络，用于在企业内部或组织内部进行通信。它提供了一种安全、可靠和高效的通信方式，可以满足企业或组织内部的通信需求。

在PISN中进行的通信需要保证同步性，以确保通信的准确性和可靠性。因此，ISO/IEC 11573:1994标准定义了同步方法和技术要求，以确保在PISN中进行的通信是可靠和准确的。

该标准定义了两种同步方法：基于时间的同步和基于事件的同步。基于时间的同步是通过使用时钟信号来同步通信设备的时钟。基于事件的同步是通过使用事件信号来同步通信设备的状态。

此外，该标准还定义了一些技术要求，以确保在PISN中进行的通信是可靠和准确的。这些技术要求包括：时钟精度、时钟稳定性、时钟偏移、时钟抖动、事件响应时间等。

总之，ISO/IEC 11573:1994标准是一项关于同步方法和私有综合服务网络（PISN）技术要求的国际标准。它定义了同步方法和技术要求，以确保在PISN中进行的通信是可靠和准确的。

相关标准
- ISO/IEC 11572:1994 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Inter-exchange signalling protocol — Call control — Supplementary services
- ISO/IEC 11574:1994 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Inter-exchange signalling protocol — Call control — Call transfer supplementary service
- ISO/IEC 11575:1994 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Inter-exchange signalling protocol — Call control — Call diversion supplementary service
- ISO/IEC 11576:1994 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Inter-exchange signalling protocol — Call control — Call hold supplementary service
- ISO/IEC 11577:1994 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Inter-exchange signalling protocol — Call control — Call waiting supplementary service