The specification should work for any realization of the system. The realization of the system contains all of the details of a particular implementation, including the user interface design and the details of how the operations of an interface will work. They are categorized under the headings of either specification or realization . As you move from the specification to the realization stage, and as the design and development moves from the analysis to implementation phases, it is possible to go back and refine things that occurred in earlier phases. Analysis Analysis, of course, is where it all begins.
Requirements analysis is done first.
These use cases are then expanded upon to describe where the system will be supporting a business process. While in the specification stage, all of the design work reflects the specification. This is information that will be the same in any realization. Operation specification is an important step in the process. This is where the operations are created and documented.