What is a primary feature of the ActiveX Control in the Historian Client?

The primary feature of the ActiveX Control in the Historian Client is its ability to provide both application-level and building block controls. This means that the ActiveX Control allows developers and users to create custom applications that can interact with the Historian data in a flexible manner. By utilizing these controls, users can design interfaces that are tailored to specific requirements and scenarios, which enhances the functionality of the Historian Client. The building blocks facilitate rapid development and deployment of applications by simplifying the process of integrating various data sources.

Other features mentioned, such as creating visual reports, managing database connections, and scheduling tasks, are functionalities typically found in different aspects or components of the Historian environment but are not the primary function of the ActiveX Control within the client. The emphasis on application-level and building block controls highlights the flexibility and adaptability that the ActiveX environment provides for users engaging with process data visualization and interaction within the Historian framework.