Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Components (hierarchy name)
4. components (objects parts)
5. [components by specific context]
6. built work divisions

Anotations

Scope note:

Sections of new construction attached to an existing built work, with the function of adding an extension or increasing the floor area or height of an existing building beyond the original building envelope.