Status: IN
Recursive structures form a self-contained subsystem in the GoF catalog with both complete infrastructure (Composite trees + Iterator traversal + Flyweight sharing) and bidirectional OCP extensibility (new element types via Composite, new operations via Visitor), making hierarchical object structures a first-class design domain.
Infrastructure completeness plus extensibility in both directions yields a closed, self-sufficient design domain
Depends on (SL): recursive-structure-complete-infrastructure, composite-visitor-dual-ocp-coverage