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. architectural elements
7. [openings and opening components]
8. openings (architectural elements)
9. [openings by form]
10. [doorways and doorway components]
11. doorway components

Anotations

Scope note:

Streams of high-velocity, temperature-controlled air which are directed downward across an opening to prevent transfer of heat across it, thus making it possible to air condition a space having an open entrance.