OptionalchannelsOptionalclassOptionalnodeOptionalonR-12c (round 21): wired by hosts that own their geometry document and can re-lay-out. When absent on a structural target, the size control is SUPPRESSED rather than offered inert, because a size override is layout input and applying it post-layout overlaps neighbours and invalidates routes.
OptionaltargetR-12b: renderer-neutral form, for structural scenes.
OptionalugmConvenience form: the editor derives the target from the
graph. Supply this OR target.
R-16 (register, 2026-08-06): the channels this target's renderer can apply. Defaults to the renderer implied by the target form (canvas for ugm/nodeId, structural for
target). Controls outside the set are not rendered.