I'm replying-to-myself, because I think this text from YAML 1.2 (explaining its changes) are key: > The primary objective of this revision is to bring YAML int

I'm replying-to-myself, because I think this text from YAML 1.2 (explaining its changes) are key: > The primary objective of this revision is to bring YAML into compliance with JSON as an official subset. YAML 1.2 is compatible with 1.1 for most practical applications - this is a minor revision. An expected source of incompatibility with prior versions of YAML, especially the syck implementation, is the change in implicit typing rules. We have removed unique implicit typing rules and have updated these rules to align them with JSON's productions. In this version of YAML, boolean values may be serialized as “true” or “false”; the empty scalar as “null”. Unquoted numeric values are a superset of JSON's numeric production. Other changes in the specification were the removal of the Unicode line breaks and production bug fixes. We also define 3 built-in implicit typing rule sets: untyped, strict JSON, and a more flexible YAML rule set that extends JSON typing." Since "no" is not the same as false, the Norway problem disappears. It's safer to always quote single-word strings like 'this', just like you always have to quote all strings in JSON.