What the source actually carried (DD-001 ethos — never fabricated).
'known' when the source reused geometry via instances (more placements than unique masters), so
the scene preserved it as GPU instancing (DD-022); 'unavailable' otherwise.
'known' when the source assigned colors/materials, else 'unavailable'.
'known' when the source declared more than one object.
'known' when the source explicitly declares plate structure (incl. an explicit single plate);
'unavailable' for undeclared/implicit plate structure (DD-025).
'known' for real per-object transforms (3MF); 'unavailable' for a bare STL.
OptionalplatesDeclared plate structure (DD-025). Present only when the source explicitly declares plates; a
consumer shows a plate selector only when capabilities.plates === 'known'. active is the source's
active/default plate id when declared (a consumer's natural initial selection — the renderer never
forces all-plates).
A presentation scene: one or more objects plus capability honesty about what the source carried.