What type of rules allow for reusable logic throughout an application in Appian?

Expression rules provide reusable logic throughout an application in Appian by encapsulating specific functionality that can be invoked from different components, such as interfaces, process models, or other expression rules. This enables developers to implement a single piece of logic once and then call it wherever necessary, promoting consistency and reducing redundancy in the application.

Expression rules can handle calculations, data manipulations, or return specific values based on the inputs they receive. By using expression rules, developers can ensure that updates to the logic need to be made in only one place, making maintenance easier and reducing the potential for errors across the application.

Other components like process models, record types, and interface rules serve different purposes within Appian. Process models are designed to automate workflows, record types define how data is structured and stored, and interface rules focus on the presentation layer, defining how users interact with the application. While these elements play crucial roles in application development, they do not inherently offer the same level of reusable logic that expression rules provide, which is specifically tailored to encapsulate and reuse programming logic across different parts of the application effectively.