UML Expanded Use Case
A UML expanded essential use case is a more detailed description of the processes used to accomplish the system function. An expanded use case is built upon a high level use case. There are two sections to the high level use case which are a heading and a body. The heading describes the name, actors, description, type of use case, and more. The body describes typical events and alternatives to the typical events. This includes two or more columns with an actor action in one column and the system response in the other column. Typical events will happen 80% or more of the time and alternatives will happen only 20% or less of the time.
One step in the course of events is not normally categorized as a use case.