[jmillikin]

See the last section -- a parser that interprets YAML as v1.2 by default will break for YAML v1.1 documents.

There's no way to determine whether a `.yaml` file is YAML v1.1 or v1.2 without a version directive, and most YAML documents are v1.1 because most YAML parsers default to v1.1 semantics.

I used Ruby as an example since it's easily available on most platforms, but you could also use Python or C++ or Swift or whatever language[1] you prefer. The underlying issue -- YAML not being a subset of JSON -- is universal.

[1] Note that some libraries, such as go-yaml, do their own thing and don't conform to either v1.1 or v1.2 semantics.