- What elements are used in UML? - Correctness of role usage - Name the elements - Identify errors - Determine the format

In UML (Unified Modeling Language), the following main elements are used:

• Actors — external entities interacting with the system (users, other systems).
• Classes — describe objects with their attributes and methods.
• Objects — instances of classes.
• Components — modules or parts of the system.
• Packages — group elements for organization.
• Associations — show relationships between elements.
• Roles — define the behavior or function that an element performs in the context of a relationship.
• Diagrams (Use Case, Class, Sequence, Activity, etc.) — different types of system representations.

Correctness of role usage: roles should be clearly defined in the context of the relationship between elements. For example, in an association between classes, a role indicates what function the class performs in this relationship (e.g., "buyer" and "seller" in a "purchase" relationship). An error would be the absence of a role where it is needed for understanding the interaction, or incorrect assignment of it.

Errors:

• Using elements outside their context (e.g., an actor inside a class diagram).
• Absence of roles when they are necessary for understanding.
• Incorrect representation of relationships (e.g., using inheritance instead of association).

Format: UML diagrams are usually created with specialized tools (e.g., Enterprise Architect, StarUML) and have a standardized graphical representation with specific symbols and notations. The file format can be XMI for data exchange between tools.