- From: Maciej Stachowiak <mjs@apple.com>
- Date: Fri, 10 Feb 2012 10:59:19 -0800
- To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
- Cc: Laura Carlson <laura.lee.carlson@gmail.com>, HTMLWG WG <public-html@w3.org>
On Feb 10, 2012, at 8:27 AM, Leif Halvard Silli wrote: > Hi Maciej, > > Thanks for the evaluation. I have, since roughly summer last year, been > comforted by the fact that Steve and the A11Y group has worked o this > issue - they submitted their re-open requests just before you published > your evaluation. Without going in detail about my faulty logic, I now > realize that I therefore ought to have withdrawn my reopen-request, to > show my support for their forthcoming - and now published - reopen > request. I hope that my lack of action does not impact negatively on > your evaluation of the new request. Indeed, the new reopen request will be considered separately, and will not be impacted negatively by this other, older request. Regards, Maciej > > regards, > Leif H Silli > > Maciej Stachowiak, Thu, 09 Feb 2012 17:27:18 -0800: >> >> Hi Leif, >> >> The Chairs have reviewed your reopen request. This Change Proposal >> does not contain explicitly identified new information, and the >> Rationale in particular does not seem to contain new information at >> all. If you would still like to pursue this reopen request, you can >> update the Change Proposal to explicitly identify new information and >> resubmit it. At that point, we will evaluate whether the new >> information likely would have been enough to materially affect the >> decision. >> >> Regards, >> Maciej >> >> On Apr 19, 2011, at 10:00 PM, Leif Halvard Silli wrote: >> >>> Hi Maciej, my assumption is that the chairs now are considering the >>> new info I provided. Do you need more detailed info? When could there >>> be a reply? >>> >>> Meanwhile, hereby follows the outline of a change proposal for the >>> generator exception. Suggestions for how to improve are much wanted - >>> send to this list or to list@html4all.org. >>> >>> CHANGE PROPOSAL (1st edit): >>> >>> A common treatment of all images without @alt. Omittance >>> without explicit permission is treated as 'invalidateable'. >>> >>> SUMMARY: >>> >>> 1 Images with omitted @alt for which the validator cannot >>> determine a condition for which HTML5 has an explicit >>> permission to omit the @alt, are classified as invalidatable >>> w.r.t. alternative text rather than as invalid, except when >>> the validator determines a situation for which HTML5 demands >>> a specific @alt usage. As HTMl5 already says, documents with >>> such IMG elements cannot be stamped as conforming. >>> >>> 2 Validators are authoring tools. They should thus list/count >>> all IMG elements with omitted @alt, in following categorizes: >>> >>> a) those which do not fall into category b), c), d) or e) >>> [Thus, for a), then omitted @alt is a de facto per-element >>> signal that this element cannot be stamped a conforming.] >>> b) those that are valid e.g. because they are the sole content >>> inside a figure with figcaption. (In the figure case, then >>> @alt represents the presence of the image = can be omitted.) >>> c) those with role=presentation (should have empty alt) >>> d) those that are the sole content of links (alt = link text) >>> e) those that fall into any other machine checkable situation >>> for which it can be given clear advice about what to replace >>> the omitted alt with. >>> >>> NOTE: A basis of this CP is the fact that UAs will and should >>> be encouraged to - or MUST - repair the lack of @alt >>> even in cases when it is valid to not have an @alt. This, in >>> turn, together with a view of the validator as an authoring >>> tool, is the basis for why validator should account for all >>> images without @alt. >>> PS: To ask that UAs not generate @alt when it is valid to drop >>> it = Accessibility decrease = Useless extra UA requirement. >>> NOTE: Validator warns that images without @alt (probably) will >>> have alt text being generated and that many images in category >>> 2a) above probably will hamper accessibility of the document. >>> >>> 3 Introduction of <style>img::alt { content:"Image.";}</style> >>> >>> >>> RATIONALE: >>> >>> This CP accepts as a fact that authors and authoring tools will >>> continue to write invalid documents w.r.t. @alt and that this may need >>> a more "soft" response than what is common for HTML4 validation. At the >>> same time, authors who rely on the validator as a authoring tool, need >>> to be made aware about the errors that prevent the document from being >>> conforming. And therefore the generator string as a silent error >>> suppressor is not useful and also introduces a range of additional >>> problems. [1] Instead we need a single system for every validator >>> service user. Additionally, HTML5 encourages @alt text to be generated >>> when @alt is lacking, and this is something that authors need to be >>> aware of even when - or if - it is valid to omit the @alt. >>> >>> DETAILS: >>> >>> [ This section should probably be replaced by exact spec text. ] >>> >>> 1) Clarification of how UAs should repair the lack of @alt: >>> >>> a) for IMG with omitted alt, alt text should be generated >>> even when the image is not required to have @alt attribute. >>> E.g. this example *does* need that the @alt text is >>> repaired for the purpose of representation of the image: >>> <figure><figcaption>Title</figcaption><img src=* ></figure> >>> >>> b) currently the spec only *encourages* such repair text. This >>> CP suggests a MUST instead. [Comments w.r.t. MUST/SHOULD ?] >>> >>> c) ALT text repair text proposal: >>> * The repair text should be: alt="Image." >>> * The repair text should be localized. >>> * The localization should be that of the UA and not >>> that of the document/element. (Because the user might >>> read a page that he/she don't understand the language >>> of. It would also be too much to require UAs to support >>> the several thousand possible translations of the string >>> 'Image.' That alt="Image." isn't localized to the >>> document language, is also a form of encouragement to the >>> author to actually do provide a useful, localized text.) >>> * AT treatment of a such generated alt="Image." may vary. >>> [This may need to be fleshed out.] >>> (I note that e.g. VoiceOver pronounces 'Image.' for most >>> non-presentational images that it detects, but that this >>> is not @alt text but more an element classification. It >>> may not make sense to say "Image: Image." Hence AT >>> should be free to not read such repair text.) >>> * HTML5's warning that authors should not rely on >>> such repair text should remain as is. >>> >>> 2) Introduction of a CSS selector for generating alt text: >>> img::alt { content:"Image.";} >>> This would allow the author to let the alt text vary per >>> document language and things like that. This CSS should have >>> no bearing on the validity of the image. >>> >>> 3) Validators should count all IMG elements with omitted @alt >>> and list their numbers (or simply list them) as follows: >>> >>> a) all IMG elements that are lacking @alt and which >>> also do not fall into category b), c), d) or e) below. >>> >>> * These images should simply be listed (or made account >>> for by telling how many they are). The validator should >>> not stamp them as an error. It should instead say that >>> it did not perform the validation that was asked for with >>> regard to @alt text = cannot stamp document as conforming. >>> [This is meant to be in line with HTML5's current >>> statement that documents with the generator string >>> are not conforming etc.] >>> Validator should also state that user agents are >>> required to generate @alt text for these images. >>> And it should also state that there is a high probability >>> that the accessibility of the document is hampered >>> because of their lack of alt text. >>> >>> b) all IMG elements that are valid but without @alt. >>> >>> * This is necessary because even when they are valid >>> without @alt, an @alt text will, nevertheless, be >>> generated. It is important that authors are made aware of >>> this consequence of leaving the @alt out: the author may >>> not be satisfied with the auto-generated alt text - etc. >>> >>> c) all IMG elements with role=presentation. >>> >>> * for these images, the validator requires that they get an >>> @alt [whether that @alt MUST or SHOULD be empty, is a >>> separate question]. This is in line with the current >>> Decision on this issue. >>> >>> d) all IMG elements that are the sole content of a link >>> >>> * for these elements, the validator must require an >>> alt text that is suitable as a link text. This is in >>> line with what HTML5 currently says about such cases. >>> >>> e) any other machine checkable situation for which the >>> validator would be able to give accurate advice etc. >>> >>> 4) Validators, themselves being HTML5-parsers, when they display >>> the checked/parsed source, MAY display this generated alt >>> text - preferably in a way which makes the author see that it >>> is generated. May be the same colour can be used as is used to >>> for "obsolete but conforming" features. >>> >>> 5) Even for documents where all IMG elements are machine checkable >>> conforming there should be an encouragement to perform detailed >>> image analysis to verify that the document really is conforming. >>> >>> IMPACT: >>> >>> Positive effects. >>> 1) solves the problem the generator exception was meant to solve >>> 2) treats all validation users the same, authoring tools & authors >>> 3) avoids having to define/guess what "hand-authored pages" means >>> 4) can still be used as solution to the "e-mail exception" >>> 5) offers "quick" validation for those in a hurry without >>> leaving out the necessary info for those who need the details >>> 6) avoids that there is is a condition (the generator exception) >>> under which all the @alt text rules are dropped on the floor >>> 7) incorporates HTML5's current notion of documents with the >>> generator string as not conforming but instead says that >>> this applies to any document where there is an omitted @alt >>> 8) more pedagogical validator services. Example: An author >>> inserts the follwoing code in a HTML5 validator: >>> <a href=link><img src=*></a> >>> Validator then reports back that the img lacks an alt text that >>> suitable as a link text. Thus the author has learned, without >>> reading the spec, that an IMG which is sole content of a link, >>> should have an @alt text which is suitable as link text. >>> This is also in line with HTML5's notion that one should not >>> insert alt text if one doesn't know what to put there: The lack >>> of @alt then becomes a pretext for the validator to try to give >>> advice about what to put there. >>> 9) Author gets statistics about how many images in this and that >>> category he/she has - this is helpful when trying to get >>> down to zero invalidatable images. >>> >>> Negative effects. >>> 1) It is still a change compared with HTML4. >>> 2) Some may prefer more direct error messages. >>> >>> CONFORMANCE CLASSES CHANGES >>> >>> 1) the special treatment of documents with the generator >>> string is dropped >>> 2) validators are required to give detailed responses when >>> validating IMGs with omitted @alt >>> 3) spec needs to classify which situations *are* machine checkable >>> and which situation aren't. Otherwise, different validation >>> services will not detect the same situations. NB: Important >>> that the spec can be expanded, in case more machine checkable >>> situations are detected. >>> 4) how to stamp documents with invalidatable img elements must >>> be specced rather well, to avoid possible misuses. >>> Perfect balance is important. >>> 5) more detailed spec + requirements w.r.t. @alt text repair >>> 6) more detailed spec + requirements w.r.t. AT and repaired @alt >>> 7) spec text with advice about how to use img::alt{}. Could e.g. >>> say that it can useful whenever it is valid to drop the @alt. >>> >>> RISKS >>> >>> 1) Risk that validator users do not understand the difference >>> between a document with invalidatable img elements and fully >>> conforming documents. >>> 2) Risk that non-conforming documents are presented as conforming, >>> against the presenter's better knowledge. (Misuse.) >>> 3) Risk that img::alt{content:"Alt text";} is misused. >>> 4) Perhaps authors will drop all @alt text and then run against >>> the validator, with the aim of only add @alt text for those img >>> elements where validator requires them? Thus a kind of "satisfy >>> the validator" behaviour. >>> 5) too complicated for validator developers? >>> 6) too complicated validation reports? (Solvable through validation >>> service design.) >>> >>> REFERENCES: >>> [1] Letter to the chairs with new info re/the generator exception >>> http://lists.w3.org/Archives/Public/public-html/2011Apr/0466 >>> >>> End of CP (1st edit). >>> >>> Leif Halvard Silli >>> >> >> >
Received on Friday, 10 February 2012 18:59:48 UTC