Documentation plays a key role as a component of design process, and a preview of a task before it comes to be executed. A well-specified task might not take less implementation time than one without documents, but one of the obvious advantages is that misunderstandings are avoided and readable specification makes it easy for the successive developers to exploit or modify the software or hardware design. Such merit is particularly useful for aviation and military applications in which reliability and maintainability are very important aspects for judging the success of a project.