Reference and Selective Reading

The reading guide supplies exact local source filenames. The GoF book index is the vocabulary reference; links to indexes are not section-level deep links.

Pressure	Candidate	Simpler or different alternative	Obligation
Interchangeable policy	Strategy	Callable or lookup table	Units, laws, ownership
Stable algorithm skeleton	Template Method	Composed functions	Step/failure order
Many reactions	Observer	Direct calls	Subscription lifetime and errors
First-class intent	Command	Function/data record	Per-execution state
Lifecycle-specific behavior	State	Transition table/switch	Guards, invalid events
Traversal without layout knowledge	Iterator	Simple loop	Laziness, mutation, cleanup
Ordered handlers	Chain	Dispatch map/pipeline	Stop/continue and terminal result
New operations on stable nodes	Visitor	Exhaustive matching	Type-by-operation coverage
Restorable local state	Memento	Immutable versions/deltas	Complete snapshot and ownership
Workflow interaction policy	Mediator	Pure coordinator	Scope, feedback, lifetime
Small rule language	Interpreter	Fixed presets/table	Grammar, semantics, resource bounds

No row mandates a class. Compare the actual change pressure and public contract.