Status: OUT
Abstract coupling — maintaining references to abstract classes rather than concrete ones — is the shared mechanism underlying Observer's subject-observer decoupling, DIP's layer independence, and the GoF's program-to-interface principle; it is the atomic operation from which most OO flexibility derives.
Abstract coupling is the recurring mechanism behind multiple OO principles and patterns
Depends on (SL): abstract-coupling-definition, gof-observer-abstract-coupling-subject-observer, dip-depend-on-abstractions-not-concretions, program-to-interface-not-implementation