That includes, functions, classes, variables, or any other named software entity."
In particular, the name of something declared in an outer circle must not be mentioned by the code in an inner circle. Nothing in an inner circle can know anything at all about something in an outer circle. This rule says that source code dependencies can only point inwards. "The overriding rule that makes this architecture work is The Dependency Rule. The principle that makes the architecture come together is called the Dependency Rule, as Uncle Bob describes:
In this blog entry I give a primer on Clean Architecture, which is a modern, scalable formal software architecture which is appropriate for modern web applications.