Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Furnishings and Equipment (hierarchy name)
4. Tools and Equipment (hierarchy name)
5. equipment
6. [equipment by process]
7. signaling equipment

Anotations

Scope note:

Safety indicators styled as signs or panels marking pipe- or transmission lines and ropeways along flight paths usually on or near an airfield. These carry information, usually numbers, intended to read from the air.