Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Visual and Verbal Communication (hierarchy name)
4. Information Forms (hierarchy name)
5. information forms (objects)
6. information artifacts
7. [information artifacts by function]
8. identifying artifacts
9. identification numbers and codes
10. identification numbers

Anotations

Scope note:

Persistent and unique identifiers assigned by national libraries, used to identify resource descriptions. There is no global standard for the contents of NBNs, but each nation may have a country-specific format.