Where and how are subsystem levels displayed within the architecture?

Subsystem levels within architecture are usually represented as layers or modules on architecture diagrams, such as component diagrams or layered diagrams. For example, in an iOS application, levels can be distinguished as: presentation layer (UI), business logic, data layer, and network layer. Each level is responsible for its own area of responsibility and interacts with neighboring layers through well-defined interfaces.

This representation helps visualize dependencies and boundaries between subsystems, making it easier to understand the architecture and maintain the code.