Introduction of the notion
Source: Pragmatic Aspect Guide; page 9
A use case is described as a sequence of actions. For any given use case, the designer draws up, more often than not, a nominal scenario and alternative scenarios. The nominal scenario describes how things work when “everything goes well” and there are no complications. The alternative scenarios are variants around the first one, either to handle additional conditions or to allow for possible disruptions (“exceptions”).
Canonical definition
A variant in the execution of a use case
