[i18n-activity] iTXt language tag description needs attention (#1609)

aphillips has just created a new issue for https://github.com/w3c/i18n-activity:

== iTXt language tag description needs attention ==
## Proposed comment

11.3.3.4 iTXt International textual data
https://www.w3.org/TR/2022/WD-png-3-20221025/#11iTXt

> The language tag defined in [[BCP47](https://www.w3.org/TR/2022/WD-png-3-20221025/#bib-bcp47)] indicates the human language used by the translated keyword and the text. Unlike the keyword, the language tag is case-insensitive. It is an ISO 646.IRV:1991 [[ISO646](https://www.w3.org/TR/2022/WD-png-3-20221025/#bib-iso646)] string consisting of hyphen-separated words of 1-8 alphanumeric characters each (for example cn, en-uk, no-bok, x-klingon, x-KlInGoN). If the first word is two or three letters long, it is an ISO language code [[BCP47](https://www.w3.org/TR/2022/WD-png-3-20221025/#bib-bcp47)]. If the language tag is empty, the language is unspecified.

There are several issues with the quoted text.

None of the language tag examples are correct! There is no primary language subtag `cn` (this should probably be `zh`?). The correct country code for the UK is `GB`, so the tag should be `en-gb`. There is no extended language subtag `bok`: Norwegian Bokmal should be tagged `nb`. Both Klingon tags are "valid" from the point of view that they are private use. However, Klingon has an ISO 693-3 code that is in the IANA language subtag registry (`tlh`).

The phrase *If the first word* is odd. It should probably use BCP47's term (subtag). Referencing ISO language codes doesn't make sense vs. mentioning the [LSTR](https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry).

I would suggest:

> The language tag is a "well-formed" language tag defined by BCP47. It consists of an ASCII string of hyphen-separated "subtags", each of which is 1-8 alphanumeric characters long. Unlike the keyword, the language tag is case-insensitive. Subtags must appear in the IANA language subtag registry. If the language tag is empty, the language is unspecified. Examples of language tags include: `en`, `en-gb`, `zh-Hans`, `zh-Hans-CN`, `ar-AE-u-nu-latn`, `x-private`. 


## Instructions: 

This follows the process at https://w3c.github.io/i18n-activity/guidelines/review-instructions.html

1. Create the review comment you want to propose by replacing the prompts above these instructions, but **LEAVE ALL THE INSTRUCTIONS INTACT** 

2. Set a label to identify the spec: this starts with s: followed by the spec's short name. If you are unable to do that, ask a W3C staff contact to help.

3. Ask the i18n WG to review your comment.

4. After discussion with the i18n WG, raise an issue in the repository of the WG that owns the spec. Use the text above these instructions as the starting point for that comment, but add any suggestions that arose from the i18n WG. In the other WG's repo, add an 'i18n-needs-resolution' label to the new issue. If you think any of the participants in layout requirements task force groups would be interested in following the discussion, add also the appropriate i18n-\*lreq label(s).

5. Delete the text below that says 'url_for_the_issue_raised', then add in its place the URL for the issue you raised in the other WG's repository. Do NOT remove the initial '§ '. Do NOT use \[...](...) notation – you need to delete the placeholder, then paste the URL.

6. Remove the 'pending' label, and add a 'needs-resolution' tag to this tracker issue. 

7. If you added an \*lreq label, add the label 'spec-type-issue', add the corresponding language label, and a label to indicate the relevant typographic feature(s), eg. 'i:line_breaking'. The latter represent categories related to the Language Enablement Index, and all start with i:.

8. Edit this issue to **REMOVE ALL THE INSTRUCTIONS & THE PROPOSED COMMENT**, ie. the line below that is '---' and all the text before it to the very start of the issue.

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Received on Tuesday, 1 November 2022 16:33:52 UTC