Section
A titled block: the line which names it, and what sits under it.
A section with no body is a statement rather than a container.
Sections nest, which is what an inventory is: its networks hold fiber arrays and stations, and its fiber arrays hold acquisitions and optical paths. depth says how far down one sits. The title is the bare line either way; a terminal sets it in by its depth, since indentation is the only nesting it has, and a panel puts it in a block inside its parent’s.