Adding code equivalents

Michael(tm) Smith mike at
Mon Dec 14 05:44:52 CET 2009

Mark Davis ☕ <mark at>, 2009-12-11 08:29 -0800:

> I agree that it would have been good to add the equivalents, not only for
> those but for the others where possible. That is, when we see "eng-840" (and
> these codes *do* occur in the wild), we can canonicalize to en-US. We are
> doing that in CLDR, and I think it would have been productive to add to
> BCP47.
> However, it would take a revision to do that, which I doubt we are up for.
> And while the Deprecated and Preferred Value does provide a mechanism that
> does work, I suspect that people would probably like a different term than
> Deprecated for such items, to indicate that they are not just not in
> canonical form, but are actually invalid -- but that they can be turned into
> valid by replacing by the preferred value.
> Cf.

Interesting. What set of data does that tool use as its source?
How does it distinguish "eng-840" from just being a completely invalid
code, and know to cite "en" as a replacement for "eng" or "eng-840"?

Was "eng" ever valid? Is it in a different class of retirement/
deprecation than the "eml" case?


Michael(tm) Smith

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