Explain Token stream notation, Event stream notation

[VladimirAlexiev]

The README says that repo includes

• Token stream notation
• Event stream notation

Where are these defined?

Would help me with questions like:

• I see only tree: in src but not 2 kinds of things
• The tree: notation is pretty self-explanatory, but what are all possible options there?
• What are the "indicator" chars allowed after =VAL ?
  • Eg =VAL " means "a string that was enclosed in double quotes" but what are all possible options?

[perlpunk]

There is the wiki, but a bit outdated: https://github.com/yaml/yaml-test-suite/wiki/Data-Point-Semantics
I think it was linked from the readme at some point.
We need time to update it since the sources were converted from testml to the new yaml files with the tree notation.