Variant reordering

Phillips, Addison addison at
Mon Jan 27 02:35:29 CET 2014

Hi Doug,

"Significant" is a relative significance determined by the user--a "more significant" subtag is one that is more important to the overall tag's meaning--and is related to the "remove-from-right" type of language tag matching/fallback. That is, you'd want to remove the "most significant" subtag last.

As such, it will usually be purely a subjective choice on the part of the user (given that most variant subtags already have Prefix guidance).

For example, suppose there were a subtag "2014" that meant "spelling reform of 2014" and another subtag "xxzzy" that referred to word choice in a spoken dialect. The order of these two subtags would depend on whether the author felt that the word choice or the spelling were more important to the meaning of the overall tag "zxx-2014-xxzzy" (or "zxx-xxzzy-2014"), as there is not specific information in either tag that makes one inherently "more significant" than the other.


Addison Phillips
Globalization Architect (Amazon Lab126)
Chair (W3C I18N WG)

Internationalization is not a feature.
It is an architecture.

> -----Original Message-----
> From: ietf-languages-bounces at [mailto:ietf-languages-
> bounces at] On Behalf Of Doug Ewell
> Sent: Sunday, January 26, 2014 5:12 PM
> To: ietf-languages at
> Subject: Variant reordering
> BCP 47, Section 4.1 ("Choice of Language Tag"), bullet point 6 has this to say
> about reordering variant subtags:
> "If a variant lists a second variant in one of its 'Prefix' fields, the first variant
> SHOULD appear directly after the second variant in any language tag where
> both occur.  General purpose variants (those with no 'Prefix' fields at all)
> SHOULD appear after any other variant subtags.
> Order any remaining variants by placing the most significant subtag first.  If
> none of the subtags is more significant or no relationship can be determined,
> alphabetize the subtags."
> What does the word "significant" mean in this context?
> I note that this section is not normative with regard to conformance or
> canonical form; it's something for humans to consider, not necessarily for
> software to enforce. But I'm curious.
> --
> Doug Ewell | Thornton, CO, USA
> | @DougEwell ­
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