Software Architect's Handbook

Content coupling

Content coupling is the highest type of coupling. It is considered so bad that it is also referred to as pathological coupling. It occurs when one module directly references the internal or private information in another module. For example, it exists when one module accesses or changes private data in another module.

Modules should never be designed to have this type of coupling. If modules have content coupling, they should be refactored so that there is a proper level of abstraction. The modules should not directly rely on the internal workings of each other.