Labels of the active atomic states.
Invoke nesting: 0 for the root.
Optionalinvokedthe state that invoked it
OptionalinvokeidThe invocation's id, for children.
The session id (the key in SystemTracker.machines).
The chart's name (or a fallback).
OptionalparentThe invoking machine's key, for children.
The session.
The session's status.
One machine of the system: the root session or an invoked child.