The abbreviation of the word Use Case Diagrams, which have been in software engineering as one of the most basic knowledge of the construction and the management software is considered.
At this stage ( UCD ) the needs of the software/hardware to connect to each other/others, and lines of communication; paths sweep algorithm linear software base, a well-known base planning is the path to making the best of trends.
of the most important they can be to the Rational Rose noted.