私有综合服务网络（PISN）是一种专用的通信网络，它提供了一系列的综合服务，如语音、数据、图像和视频等。PISN的主要特点是具有高度的可靠性、安全性和灵活性，可以满足不同用户的需求。为了进一步提高PISN的性能和可靠性，ISO/IEC 13242:1997标准规定了路由限制类附加网络功能的规范、功能模型和信息流。

路由限制类附加网络功能是指一种可以限制呼叫路由的功能，它可以根据用户的需求，限制呼叫的路径和目的地。这种功能可以提高PISN的安全性和可靠性，防止未经授权的用户访问网络资源。ISO/IEC 13242:1997标准规定了路由限制类附加网络功能的实现方式和操作流程，以确保PISN的正常运行。

ISO/IEC 13242:1997标准还规定了PISN的功能模型和信息流。功能模型描述了PISN的各种功能和服务，包括呼叫控制、用户认证、路由选择、媒体传输等。信息流描述了PISN中各种信息的传输方式和流程，包括呼叫请求、呼叫确认、媒体传输等。这些信息流程的规范化可以提高PISN的互操作性和可靠性，确保各种设备和系统之间的兼容性。

总之，ISO/IEC 13242:1997标准规定了PISN中路由限制类附加网络功能的规范、功能模型和信息流，它可以提高PISN的性能和可靠性，满足用户的需求。

相关标准
- ISO/IEC 11579-1:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Part 1: Protocol specification
- ISO/IEC 11579-2:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Part 2: Protocol implementation conformance statement (PICS) proforma
- ISO/IEC 11579-3:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Part 3: Abstract test suite (ATS) and protocol implementation extra information for testing (PIXIT)
- ISO/IEC 11579-4:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Part 4: Protocol implementation extra information for testing (PIXIT) for the support of supplementary services
- ISO/IEC 11579-5:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Part 5: Protocol implementation conformance statement (PICS) proforma for the support of supplementary services