Planner Notes documentation

[borndigital]

I am knowledge gathering via the documentation (https://canvas.instructure.com/doc/api/planner.html#method.planner_notes.index) and struggling to find answers to certain question by browsing and reading the documentation in-depth, searching in-page content, and can't see any info in the forums, so I'm asking questions here 

1. What are all available values of the "workflow_state" field in PlannerNote object and what do they mean in terms of API interaction and system interactions?
   I've managed to find only 2 "state" values, are there others?
   active - from documentation,
   deleted - got that by sending a "delete" API call on an existing test note - API GET for planner notes will not return this "type" of planner note, clearly.
2. What is the character limit (if any) for “title” field (for POST and PUT)?
3. What is the character limit (if any) for “details” field (for POST and PUT)?
4. Assuming (from the documentation) a planner note can be unassigned OR assigned only to a Course (no other object)?
   
   Thanks