A functional method must have which of the following?

A functional method in ABAP is designed to encapsulate a specific functionality and return a value. The characteristic feature of such a method is that it can have an output via a returning parameter. This means that when the method is executed, it should provide a result that can be captured by the caller.

The returning parameter is crucial because it allows the functional method to convey the result of its operations back to the code that initiated its execution. This aligns well with the principles of modular programming, where a method performs a task and provides an output, enabling better code reuse and maintainability.

While methods can include importing, exporting, or changing parameters, the unique function of the returning parameter is to specifically serve as the definitive output for the method, distinguishing it from parameters designed for input or state changes.