W3C home > Mailing lists > Public > public-pfwg@w3.org > January 2014

Re: CSS Counter Styles Level 3 revisted

From: James Craig <jcraig@apple.com>
Date: Mon, 20 Jan 2014 09:44:40 -0800
Cc: public-pfwg <public-pfwg@w3.org>
Message-id: <5EDA50BA-8266-48FA-B8BC-5A26A7B62D56@apple.com>
To: "lisa.seeman" <lisa.seeman@zoho.com>

Before this goes out as public WG feedback, I think we should suggest a fix.

I think this could possible be covered by extending the CSS4 “alt” property [1]. Current discussion only allowed its use on pseudo elements. E.g. 

li::before {
    content: counter(box-corner);
    alt: counter(numbered);
}

But the CSS ‘alt’ property could possibly be extended to be part of the counter declaration so that each use of the counter style would get it by default:

@counter-style box-corner {
    system: fixed;
    symbols: ◰ ◳ ◲ ◱;
    alt: '1' '2' '3' '4';
    suffix: ':';
}

[1] Alt in CSS4 on generated content pseudo elements:
http://lists.w3.org/Archives/Public/www-style/2012Nov/0318.html

On Jan 14, 2014, at 10:54 AM, lisa.seeman <lisa.seeman@zoho.com> wrote:

> Hi. 
> I was asked to explain the comments made on CSS Counter Styles Level 3 (see http://www.w3.org/TR/2013/WD-css-counter-styles-3-20130718/)
> 
> I have given some clarifications/ examples here on the two issues we raised. The original email and responce is bellow the clarifications. Anything in quotes is copied directly from the specification. 
> 
> And now to the main: We had two comments:
> 
> Comment 1 was to support accessible usage
> To support accessible usage we suggested: 
> 1.1. It should be a requirement that accessible content alternative is provided (when content is inaccessible) and
> 1.2 All examples in the specification should support accessibility.
> 
> To clarify this with examples from the specification:
> The counter style can change the meaning - for example " a negative sign, which is prepended or appended to the representation of a negative counter value. "
> The style can give information that is not machine understandable for example " cyclic counter styles just cycle through their symbols"
> These styles can have meaning (such as a tick for a correct example and a cross for a false example)
> 
> The specification supports a spoken form ("speak-as"), which describes how to read out the counter style in a speech synthesizer. However the examples of symbols in the specification did not use a speak-as alternatives, and speak-as is not required when symbols or counter style convay invformation
> 
> 
> Example from the specification
> "
> @counter-style box-corner { system: fixed; symbols: ◰ ◳ ◲ ◱; suffix: ':';}
> 
> 
> Comment 2: Accessibility API mapping
> We requested information for how user agents, such as a browser should should map this specification to the accessibility API. 
> 
> It needs to be specified especially as a "speak-as" option is not a requirement, so we can not rely on that.
> 
> for example: WHat cshould be mapped when there is a fall back counter style and no "speek-as" option ?
> what about when the "speak-as" option is out of range.
> 
> Should APIs map to the fall back value all the time if there is no "speak-as"?
>  
> Note: "If the value of the fallback descriptor isn't the name of any currently-defined counter style, the used value of the fallback descriptor	is decimal instead. "
> 
> Looking at two example from the speck:
> "@counter-style decimal-leading-zero { system: fixed -9; symbols: '-09' '-08' '-07' '-06' '-05' '-04' '-03' '-02' '-01' '00' '01' '02' '03' '04' '05' '06' '07' '08' '09';}"
> and
> "@counter-style cjk-decimal { system: numeric; symbols: \3007 \4E00 \4E8C \4E09 \56DB \4E94 \516D \4E03 \516B \4E5D; /* 〇 一 二 三 四 五 六 七 八 九 */ suffix: '\3001'; /* "、" */}"
> 
> Note that for both examples
> 	• no "speak-as" is provided
> 	• the default fallback is decimal
> 
> For each example - what should be mapped to the accessibility API ? How should the browser work that out?
> I would guese that the decimal default works well for the second example, and not at all for the first example. But how does the browser know that? 
> 
> All the best
> Lisa
> 
> should 
> in an interoperable manner. This> means that different browsers will do it differently and often incorrectly.> Hence, the author will not be able to make accessible content.>
> 
> 
> 
> >> Comment 1: Support accessible usages>> In general we think it is possible to make accessible content using this> specification. However, we feel that it will not be clear to users how to> make accessible content, and a lot of content that conforms to this> specification may not be accessible. We propose that:>> It should be a requirement that accessible content alternative is provided> (when content is inaccessible);> All examples in the specification should support accessibility.>> For example, it may be be possible, by having a fallback class with the> "speakas" option, to create what is essentially alt text for symbols. In> cases like this - where symbols represent true information - a text> equivalent fallback class should be not just possible but a requirement. If> it is considered inappropriate to require this we would at least like it to> be best practice.I don't fully understand this feedback. The counter styles defined by@counter-style cannot be used to format arbitrary text; they're onlyusable to format list item bullets (via the list-style-type property)and CSS counters (via the counter() and counters() functions). Inparticular, it's not usable, except perhaps in an extremely hacky androundabout fashion, as a way to produce symbols in text, like "symbolfonts" are used for.It's far easier to produce symbols in the proper, accessible way.
> 
> 
> 
> 
> 
> 
> 
> > Comment 2: Accessibility API mapping>> It is not clear how user agents (assistive technology and browsers) should> support this specification to provide consistent accessibility support. Many> assistive technology's (AT) work via an accessibility API (AAPI), where the> browser populates a custom data structure in the AAPI and the AT present> that information in the way best suited to the user's needs. More> information on this topic can be found at> http://www.w3.org/TR/wai-aria-roadmap/.>> At present there is not information for how user agents should should map> CSS features cases to the accessibility API in an interoperable manner. This> means that different browsers will do it differently and often incorrectly.> Hence, the author will not be able to make accessible content.>> We would like specification to specify the mapping of these attributes and> classes to the user agent and accessibility API of the operating system.> This will enable user agents to know how to correctly support the> specification, which would make it much more likely that accessibility will> not just be theoretically supported, but to be actually and correctly> supported by user agents. We are happy to work with you on how to do these> mappings.>> There are two other advantages to doing this. Firstly it will also give us a> clear way to determine if and when user agent support is sufficient to> allow authors to use this specification. FYI, as many large sites are> required to provide accessible content, and then accessibility support for> real users is a legal requirement. In such cases authers will not be alowecd> to adopt this specification becuse the browsers implemented the> accessibility support incorrectly.>> Secondly, creating these mapping would test that that the specification is> not missing any information / attributes / requirements that would enable> sensible meaningful mapping and transfer of information to different> assistive technologies.> If we make mappings based on complex use cases we will ensure all the> information that is visually implied is also available in the mapping.> There are some cases where we would like to see the mapping as soon as> possible so we can be sure accessibility support is possible. These include:>> Symbols - cases where symbols can be mapped directly and where they can> not;> When there is a fallback class - what criteria makes the fallback get mapped> to the accessibility API as a pose to the original? Is there a requirement> to specify this;> Counter symbol;> Pad <integer> && <symbol>.I believe that 'speak-as' correctly describes the accessibilitymapping. If it doesn't, can you describe what is missing? I'm notfamiliar with the accessibility APIs directly, but so far as Iunderstand, indicating that a list is bulleted or numbered isstandard, and I suspect that lists "numbered" with letters are alsopossible to express in the APIs, so as to properly indicate nestedlists. That's the totality of what 'speak-as' can do, so I'm not surewhat else needs to be specified.
> 
> All the best
> 
> Lisa Seeman
> 
> Athena ICT Accessibility Projects 
> LinkedIn, Twitter
> 
> 
> 
Received on Monday, 20 January 2014 17:45:16 UTC

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