Use Case Specification

A brief description of the purpose and example of use

The event stream includes the basic flow and alternative flows. The basic flow describes the basic process of the use case, which refers to the scenario when the use case is "normally" running.

The same use case can have many different situations in actual execution, which are called use case scenarios,
or it can be said that use case scenarios are instances of use cases.

Special requirements refer to non-functional requirements and design constraints of a use case. Special requirements are usually non-functional requirements, including reliability, performance, usability, and scalability. For example, legal or regulatory requirements, application standards, and the quality attributes of the system being built.

The state that the system must be in before the execution of an example. For example, a precondition is to require the user to have access rights or to require that a certain use case must have been executed.

A set of possible states the system may be in after a use case is executed.
For example, it may be required to execute another use case after a certain use case is executed.