ISO/TS 17425:2016规定了车内标识服务和应用程序，该服务和应用程序向其站点（车辆ITS站点或个人ITS站点设备）提供有关道路和交通状况的车内标识信息，并由道路管理局/运营商按照道路管理局/运营商的要求进行认证，以与道路标志或可变信息标志（VMS）上显示的信息一致的方式。 注:可变消息符号也称为动态消息符号。 这两个术语都被视为同义词，可以互换使用。在下文中，仅使用可变消息符号及其缩写词VMS。 ISO/TS 17425:2016定义如下: -车内标识服务和车内标识应用程序，该应用程序实例化了该ITS服务； -车内标识服务应满足的要求； -使用ITS车站设施层提供的功能的要求，以支持车内标识服务的使用； -ITS-S应用程序在不同的ITS站点中进行处理，以实例化车载标识及其服务。 ISO/TS 17425:2016还规定:使用ISO/TS 17423中定义的方法，为车内标识服务范围内各站点之间的每个通信流选择性能水平（尽力或实时等）、可信度和安全性（认证、加密等），确定通信要求和目标（概要）。 本技术规范定义了ITS车站设施层（ISO/TS 17429）提供的相关功能和程序的选择，并定义了信息结构、内容、语法和ITS使用的原子元素- 车辆标识应用。 注:本应用程序通俗地称为“车内标识”。 车内标识服务包括车载信息管理。这种管理确保最终用户及其服务的上下文一致性（例如，车辆特征、信息优先级等。除其他外，避免向最终用户呈现冲突信息）。 本技术规范不包括支持车内标牌应用的信息的制作、资质及其相关性。 ISO/TS 17425:2016未规定车内人机界面（HMI）的设计，但规定了此类界面应能够支持的要求，以允许正确传播和使用车内标识服务提供的信息。

ISO/TS 17425:2016 specifies the In-Vehicle Signage service and application that delivers In-Vehicle Signage information to ITS stations (vehicle ITS stations or personal ITS stations devices) concerning road and traffic conditions, qualified by road authorities/operators, in a consistent way with road authority's/operator's requirements, in the manner that is coherent with the information that would be displayed on a road sign or variable message sign (VMS). NOTE A Variable Message Sign is also named dynamic message sign. Both terms are considered as synonyms and can be used interchangeably. In the text below, only variable message sign and its abbreviated term VMS are used. ISO/TS 17425:2016 defines the following: - the In-Vehicle Signage service and the In-Vehicle Signage application that instantiates this ITS service; - the requirements to be fulfilled by the In-Vehicle Signage service; - the requirements for using functions provided by the ITS station facilities layer supporting the use of the In-Vehicle Signage service; - the ITS-S application processes in the different ITS station, that instantiate the In-Vehicle Signage ITS service. ISO/TS 17425:2016 also specifies: the sets of communication requirements and objectives (profiles) using the methods defined in ISO/TS 17423 to select the level of performance (best effort or real-time, etc.), confidence and security (authentication, encryption, etc.) for each communication flow between ITS stations in the scope of the In-Vehicle Signage service. This Technical Specification defines the selection of relevant functions and procedures provided by the ITS station facilities layer (ISO/TS 17429) and defines the message structure, content, syntax, atomic elements to be used by the In-Vehicle Signage application. NOTE This application is colloquially called "In-Vehicle Signage". The In-Vehicle Signage service includes the on-board information management. This management ensures contextual coherence of the end-user ITS service (e.g. vehicle characteristics, message priority, etc. avoiding amongst others things the presentation of conflicting information to end-users). The production of information supporting the In-Vehicle Signage application, its qualification, and its relevance are out of the scope of this Technical Specification. ISO/TS 17425:2016 does not specify the design of in-vehicle Human Machine Interfaces (HMI), but it does specify requirements that such interfaces shall be capable of supporting in order to permit the correct dissemination and use of information provided by the In-Vehicle Signage service.