Re: [Ltru] Re: Registry change of the day: prefix with more than one subtag

Addison Phillips <> Tue, 10 July 2007 13:12 UTC

Return-path: <>
Received: from [] ( by with esmtp (Exim 4.43) id 1I8FVa-0007Av-Q2; Tue, 10 Jul 2007 09:12:02 -0400
Received: from ltru by with local (Exim 4.43) id 1I8FVZ-0007Ad-Op for; Tue, 10 Jul 2007 09:12:01 -0400
Received: from [] ( by with esmtp (Exim 4.43) id 1I8FVZ-0007AV-DI for; Tue, 10 Jul 2007 09:12:01 -0400
Received: from ([]) by with esmtp (Exim 4.43) id 1I8FVK-0004uU-VC for; Tue, 10 Jul 2007 09:12:01 -0400
Received: from [] ( []) (authenticated bits=0) by (8.13.8/8.13.6/y.rout) with ESMTP id l6AD9axq098978 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 10 Jul 2007 06:09:37 -0700 (PDT)
DomainKey-Signature: a=rsa-sha1; s=serpent;; c=nofws; q=dns; h=message-id:date:from:user-agent:mime-version:to:cc:subject: references:in-reply-to:content-type:content-transfer-encoding; b=spG96KHIj1bEL4hQGFYBMX9OX2+H1zOeWSUYyeZcemItZ3PRhkAaeZ54a1U/1ZTF
Message-ID: <>
Date: Tue, 10 Jul 2007 06:09:33 -0700
From: Addison Phillips <>
User-Agent: Thunderbird (Windows/20070604)
MIME-Version: 1.0
To: Doug Ewell <>
Subject: Re: [Ltru] Re: Registry change of the day: prefix with more than one subtag
References: <> <006501c7c2b7$126dd4e0$6401a8c0@DGBP7M81>
In-Reply-To: <006501c7c2b7$126dd4e0$6401a8c0@DGBP7M81>
Content-Type: text/plain; charset="UTF-8"; format="flowed"
Content-Transfer-Encoding: 7bit
X-Spam-Score: -15.0 (---------------)
X-Scan-Signature: d8ae4fd88fcaf47c1a71c804d04f413d
Cc: LTRU Working Group <>
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Language Tag Registry Update working group discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>

Doug Ewell wrote:
> <<
> Most variants that share a prefix are mutually exclusive. For example, 
> the German orthographic variations '1996' and '1901' SHOULD NOT be used 
> in the same tag, as they represent the dates of different spelling 
> reforms. A variant that can meaningfully be used in combination with 
> another variant SHOULD include a 'Prefix' field in its registry record 
> that lists that other variant. For example, if another German variant 
> 'example' were created that made sense to use with '1996', then 
> 'example' should include two Prefix fields: "de" and "de-1996".
> A human can easily see that "de-1901-1996" and "sl-rozaj-njiva" are 
> meaningless, because the variants are clearly contradictory.  But a few 
> variants with the same prefix can in fact be used together, such as 
> "en-scouse-fonipa" or "en-boont-fonipa".  

Uh... fonipa has no prefix, so it doesn't share a prefix with either 
scouse or boont.

In fact, 'fonipa' and 'fonupa'
> have no prefix and can thus theoretically be used with any tag, but some 
> combinations like "el-monoton-fonipa" are inappropriate nonetheless.

Yep. We have no mechanism for saying this. This would fall under the 
rubric of "Tag Content Wisely"
> At you can find an 
> illustration of this situation.  The drop-down list of variant subtags 
> for "sl-rozaj" shows not only the reasonable choices, like 'fonipa' (no 
> prefix) and 'njiva' (prefix = "sl-rozaj"), but also the inappropriate 
> 'nedis' (prefix = "sl").

Ur... nedis and rozaj share a prefix and thus fall under the general 
exclusion rule.

> What information is available in either RFC 4646(bis) or in the Registry 
> that would help software to make this decision?  Does a prefix of 
> "language with no variant" mean that the variant should not be used in 
> the presence of any other variant?  

That is, in fact, what the RFC says. How else should we interpret:

 > Most variants that share a prefix are mutually exclusive.

How does one determine that
> "en-scouse-fonipa" is OK while "el-monoton-fonipa" is not?

Not via Prefixes. I'll note that "el-AQ-monoton" is also a dubious 
choice. There is an upper limit to the amount of information we can pack 
into the registry, I think. We could add the following text after the 
quoted paragraph though:

Some variants have no Prefix or have several different primary language 
prefixes. Such variants might be useful in combination with other, 
similar variants or with variants specific to a given language. This 
isn't always true and care is called for in selecting between these 
subtags. For example, a tag like "el-monoton-fonipa" is probably 
ill-considered, since both 'monoton' (Monotonic Greek) and 'fonipa' 
(International Phonetic Alphabet) can't both be used to transcribe the 
same document at the same time.


Addison Phillips
Globalization Architect -- Yahoo! Inc.
Chair -- W3C Internationalization Core WG

Internationalization is an architecture.
It is not a feature.

Ltru mailing list