Note that NO is no longer a boolean literal in YAML 1.2 (which came out in 2009) so Norway hasn’t been a good example for almost 15 years. The two remaining strings to watch out for is true and false. I’m not sure I agree with this decision; since I was resigned to the idea that I can’t eyeball a YAML document’s validity and bug-free-ness, and that’s a pretty huge downside to a document format but the upside is how human-friendly it read.
has-paid: no
delivered: yes
Nice! But no longer possible in the current version.