Need specifics on unified JSON test output
Kaitai Struct uses a specific JSON schema for test output.  
I want to target it directly from my target language (Nim) but it is not documented anywhere.

After some experimenting I found out the following keys are supported:
- status
- elapsed
- is_kst

Questions:
1. Are there other keys supported?
2. What exactly does the key `elapsed` mean?
3. What are all the possible values for the key `status`?

Ideally someone should make an official documentation about this.