Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Components (hierarchy name)
4. components (objects parts)
5. [components by general context]
6. hardware (components)
7. [hardware by form]
8. finish hardware (hardware)
9. accessory door hardware

Anotations

Scope note:

Appendages, usually of iron or brass, fastened to a door and hinged so that it may be made to strike against a metal plate or the door itself, to attract the attention of those within. Door knockers are usually placed on exterior doors.