Classes are Basic model elements. Class names are shown in boldface type. Abstract classes are shown in italic. Objects (class instances) are shown by class elements with underlined names. Class name or object name may be elided (anonymous). Interfaces are indicated by lollipops. No implementation just operations are provided. Collaborations are indicated by dashed ovals. They realize use cases. Use case is shown as an ellipse; it shows a functionality of the system for the external user. Active classes are shown by thick bordered class boxes; they represent independent thread of processing. A component is a combination of one or more classes that forms a physical software. A node is a processor or device (a physical hardware). A composite model element is a package or a subsystem of base or composite elements.