You can find it by looking in <parentLocales> here https://github.com/unicode-org/cldr/blob/main/common/supplemental/supplementalData.xml#L5119

Note: English is a lingua franca and inheritance is not specified for all the English locales right now. If inheritance is not specified it will inherit from the parent locale 'en'.

Best,

Annemarie

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On Tue, Mar 10, 2026 at 12:03 PM Guy Harris via tz <tz@iana.org> wrote:
On Mar 10, 2026, at 10:01 AM, Mark Davis Ⓤ <mark@unicode.org> wrote:

A brief note of explanation (since not everyone will have read the spec!)

"The spec" presumably being https://unicode.org/reports/tr35/ (and, in particular, https://unicode.org/reports/tr35/#Locale_Inheritance?).
  1. CLDR uses inheritance, so child locales inherit from their parents. Eg fr_CA (French as used in Canada) inherits from fr (French as used in France, = fr_FR)
  2. <...>∅∅∅</...> blocks that inheritance for a particular item, meaning that there will be no value for that locale; the reason for doing that is when the item is not generally understood / used in the locale (such as unfamiliar abbreviations). 
  3. For time zones, when there is no value, an alternative is used (eg UTC-7). 
  4. en_001 is the ancestor of most English variants.
So what is the inheritance hierarchy? Where do en.xml (which, as noted, uses "Australian" in the long names for EST/EDT, CST/CDT, etc. in Australia) and en_001.xml (which says nothing about Australia) sit in that hierarchy?

As for the abbreviations, en_AU.xml has abbreviations that begin with "A", which may make it unique but, as I understand what Robert Elz has said, does not match the abbreviations used in Australia.