Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Object Genres (hierarchy name)
4. object genres (object classifications)
5. [object genres by form]
6. chains (object genres)

Anotations

Scope note:

Chains comprising transverse blocks or cylinder units, joined by side links and held in place by pins. The blocks engage a driving wheel with teeth. An example of a block chain is used to rotate bicycle wheels and on other mechanical devices.