Every public RealityKit component type — which SDK versions expose it, whether Reality Composer Pro surfaces it in the Add Component menu, and what's platform-exclusive.
latest RCP findings
OpenUSD has a closed, enumerable set of SdfValueTypeNames. Swift's type system is open-ended and Turing-complete. RCP cannot support all Swift types — it supports the USD-serializable subset: Swift types that map directly to SdfValueTypeNames, plus special cases like enums, arrays, and optionals.
Apple's WWDC 2023 session 'Work with Reality Composer Pro content in Xcode' explicitly defines custom component type constraints. The session demonstrates PointOfInterestComponent with String, custom enum, and Optional<String> fields, and warns that Xcode produces errors for types RCP cannot serialize.
The particle emitter fixture set is large and sparse-authored. The canonical shape is `RealityKit.VFXEmitter` with `currentState`, `mainEmitter`, and `spawnedEmitter`, and the most useful public references are now the schema page plus per-component CSV exports.