Source of the example inputs
============================
ifc/example-room-master.ifc, proofs/glb/model.glb and items/table.work.1600/table.work.1600.item.json are copied unchanged from the
builders guide 2.3.0 sample delivery deliveries/example-room/ (offered under CC BY 4.0; the item description file under Apache-2.0).
semantic/semantic.json is new. It was started with derive/derive_sidecar.py and finished by hand; the ids were then renamed
(for example room.example-work-room became room.work) and the uses, the two virtual items (the story notebook and the door key),
the phenomena, sensing links and cameras were written by hand.

Known property of the sample: the table's item description has a seat point for a chair, but the sample room contains no chair.
The example keeps the seat point (anchor at.work-table.sit) to show a sit anchor; a real room would model the chair.
