This International Standard provides a generic request eply-oriented data access mechanism for applications from independent suppliers to access CIM data in combination with IEC 61970-402: Common Services. An application is expected to use the Generic Data Access (GDA) service as part of an initialisation process or an occasional information synchronization step. GDA is generic in that it can be used by an application to access any CIM data. GDA is also generic in that it also provides a back end storage mechanism independent query capability that can be used to facilitate the creation of CIM data warehouses. This specification provides a simple@ concise service that meets the functionality requirements of current and future applications while: ?avoiding unnecessary complexity; ?not requiring any specific database technology for implementation. This service is designed to support interaction where the application or system requesting information is developed@ supplied@ maintained@ or operated by a separate agency from the application supplying the data. Furthermore@ the update portion of this service assumes that it is undesirable for one system to directly write into another. To support these objectives@ the GDA capabilities are divided into three categories: a) read access; b) update access; c) change notification events. It should be noted that the update portion of this service does not support unconditional access to critical real-time data. Rather@ the update portion allows a requesting application to ask for data to be changed in a service provider@ but the service provider is under no obligation to carry out that change at any particular time. Furthermore@ a positive response from the update service does not indicate that the update has occurred@ but only that the service provider has successfully received the request and that the request is syntactically and semantically correct. GDA could be classified as an Enterprise Information Integration (EII) technology adapter specialized to the power industry via the assumed use of the CIM. There are a number of EII products currently available on the market@ but there is no accepted cross-platform standard for writing connectors for these products and overall these products do not take full advantage of a common semantic model such as the CIM. In recommending GDA@ WG 13 is recommending a standard EII connector model in the form of a simpler@ less expensive@ and more specialized interface. Though the target of this IEC standard includes the utility control center technical domain@ generic data access encompasses a general set of concepts that can be applied to many types of systems. Examples of these systems include: ?Energy and distribution management systems ?Work and asset management systems ?Geographic information systems ?Outage management systems ?Other types of technically oriented operational business systems. In recognition that the integration between applications in two or more of these systems is often necessary@ the intent of this specification is to address general GDA requirements to the extent that they are common to different types of systems while effectively addressing utility operation application specific needs.