Earlier quoted context omitted.
“The Norway Problem” YAML has: when you abbreviate Norway to its ISO 3166-1 ALPHA-2 form NO, YAML will return false when parsing list of countries f.e ‘[GB, IN, NO,…]’
It's a good example of how you can overengineer a relatively simple format. The reason is that they specify a boolean value as either "true/false" or "yes/no". The last alternative causes problems not only for the Norwegian country code (no), but also in cases where you need to specify the actual word "yes" You could of course end up with the same problem if you need to specify the literal "true" and "false", but by…
A Boolean represents a true/false value. Booleans are formatted as English words (“true”/“false”, “yes”/“no” or “on”/“off”) for readability and may be abbreviated as a single character “y”/“n” or “Y”/“N”.
Regexp: y|Y|yes|Yes|YES|n|N|no|No|NO|true|True|TRUE|false|False|FALSE|on|On|ON|off|Off|OFF