Children
A trait's definition can indicate if it has child things, and, if so, how those things behave and what traits the children themselves implement.
For example, the scene trait allows a thing to save the values of the properties in its state section and associating them with a scene-id. The scene itself is represented as a child thing that can be manipulated independently.
Each child thing can be identified by a combination of the trait identifier and a child-id.
For example, if I used f/scen?save to create a scene with a scene-id
(child-id) of evening, the resulting child would be identified by
the tuple (scen, evening).
The exact mechanism for how you reference children is implementation
specific, but in SMCP for example, it would be referenced as
f/scen/evening/, relative to the parent.
The nesting of child things is allowed.