Alias locales are extracted from the very convenient DateTime::Locale::Catalog which is a Perl binding to Unicode CLDR data.

However, it is not clear whether some variants are really pertaining as alias locales since some of them might be constructs inherited from DateTime-Locale and not CLDR:

• International/world variants (code {001}):
  • World English ({en_001}) is in Unicode CLDR but European English ({en_150}) is not in DateTime-Locale; See https://www.ctrl.blog/entry/en-001.html
  • World Arabic ({ar_001}) is in DateTime-Locale but not in Core CLDR data;
  • Some other languages have such debatable variant too.
• Unique variants for languages used in a single country ({et_EE}, {fi_FI}...)