UML. What elements are used? Correctness of role usage. Name the elements. Identify errors. Define the format.

In UML (Unified Modeling Language), various elements are used for system modeling, among which the main ones are:

• Actors — roles that interact with the system (e.g., user, external service).
• Classes — describe objects with their attributes and methods.
• Objects — specific instances of classes.
• Use Case Diagrams — show interactions between actors and the system.
• Class Diagrams — describe the structure of the system.
• Sequence Diagrams — display the order of interactions between objects.

The correctness of role usage involves properly defining actors and their interactions with the system. For example, an actor should represent an external user or system, not an internal component.

Errors can include:

• Incorrect role definitions (e.g., an internal class is labeled as an actor).
• Lack of connections between actors and use cases.
• Using inappropriate elements in diagrams (e.g., a class in a use case diagram).

UML format is a standardized modeling language with a clearly defined notation, supported by many tools. For correct usage, it is important to adhere to standard symbols and diagram construction rules.