- From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
- Date: Fri, 10 Feb 2012 17:27:18 +0100
- To: Maciej Stachowiak <mjs@apple.com>
- Cc: Laura Carlson <laura.lee.carlson@gmail.com>, HTMLWG WG <public-html@w3.org>
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 Without going in detail about my faulty logic, I now realize that I therefore ought to have withdrawn my reopen-request, to show my support for their forthcoming - and now published - reopen request.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. 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 16:27:49 UTC