It used an off-the-shelf library, I don't remember which one anymore. I don't think it really matters though -- YAML is a format, not a parser.

Per the YAML docs [0], "Creating a fully compliant parser has proven almost impossible." Pretty much every YAML parser out there is going to have its own idiosyncratic subset that it handles. That doesn't make the _files_ not-YAML.

(This does make YAML a horrible data exchange format. No argument there!)

Also, JSON has a similar condition [1].

[0]: https://github.com/yaml/yaml-grammar [1]: http://seriot.ch/projects/parsing_json.html