Status: IN
Visitor's operation extensibility is broadly flexible in both structure type and class hierarchy: it can traverse various object structures (composites, sets, lists, DAGs) and does not require a common parent class among visited objects — making it one of the most general operation-extension mechanisms in the GoF catalog.
Two independently stated Visitor generality properties (any structure, no common parent) establish Visitor as universally applicable for operations
Depends on (SL): visitor-traverses-any-object-structure, gof-visitor-no-common-parent-required