What do preconditions normally describe in a fully developed use case description?

Preconditions in a fully developed use case description normally describe the state of the system before the use case begins. They set the stage for the actions that will follow in the use case. Here are the steps to understand it:

1. Identify the Use Case: The first step is to identify the use case for which you want to define the preconditions. A use case is a specific situation in which a system or application interacts with users or other systems.

2. Understand the System: To define preconditions, you need to have a thorough understanding of the system or application. This includes knowing its current capabilities, its limitations, and how it interacts with users or other systems.

3. Define the Preconditions: Preconditions are the conditions that must be met before the use case can start. They describe the state of the system before the use case begins. For example, if the use case is "User withdraws cash from ATM", a precondition might be "The user has a valid bank card and the ATM has enough cash".

4. Document the Preconditions: Once you have defined the preconditions, document them in the use case description. This will help anyone reading the use case to understand what needs to be in place before the use case can begin.

5. Review and Update: As the system or application changes, the preconditions may also need to change. Regularly review and update the preconditions to ensure they remain accurate and relevant.