What is the function of an Expression Rule in the application design?

The function of an Expression Rule in application design is primarily to return dynamic data through stored expressions. Expression Rules in Appian are designed to encapsulate specific logic or computations that can be reused throughout the application. This allows developers to create complex expressions once and then call them whenever needed, promoting code reusability and maintainability.

By returning dynamic data, Expression Rules can effectively respond to different inputs, calculations, or conditions within the application, providing a powerful way to handle data processing and logic implementation. They serve as a key part of Appian's functionality, enabling developers to create dynamic decisions and outputs based on user interactions or system changes.

Other options address aspects that are not core functions of Expression Rules. For instance, managing user roles pertains to security and access control, and is handled through different mechanisms in Appian. Outlining a development schedule is more related to project management rather than technical application design. Lastly, providing a minimum viable product is a concept related to product development strategy, focusing on delivering a basic version of an application, rather than the specific technical implementation of dynamic logic through Expression Rules.