Documentation of Sched_context

Hi,

what exactly is represented by a Sched_context?
'sched_context-fixed_prio.cpp', for example, contains members called
'_prio' and '_quantum'. That would suggest that a Sched_context is a
schedulable object like a task or a thread.
However, the file mentioned above defines some sort of ready queue, too.
That would indicate that a Sched_context is some part of the scheduler
that organizes the schedulable objects in a data structure?

Where are all those classes documentated? Using the search box, the
official documentation (http://os.inf.tu-dresden.de/L4Re/doc/index.html)
does not offer any information about these.

Best regards,
Valentin Hauner