- From: Jeanne Spellman <jeanne@w3.org>
- Date: Thu, 16 Jan 2014 15:04:15 -0500
- To: UAWG <w3c-wai-ua@w3.org>
The User Agent Accessibility Guidelines Working Group (UAWG) was asked by the Protocols and Formats Working Group (PFWG) to review the Resource Priorities FPWD. We would like to make the following comments: 1) [minor] In the code example in 1.2 Optimizing download priority during network contention (and other code examples) there are images with no alternative text. Please change them to show best practices. (E.g. <img id="Logo" src="/images/Logo.png" alt="XYZ organization"/> ) 2) In section 4.3 The @postpone attribute: The IF condition does not appear to accommodate linear browsers, such as a screenreader, which reads the page without scrolling. It is possible that the screenreader would not change the User Agent's interpretation of the document's viewport, and the material would not be downloaded or read to the user. Please keep in mind that screenreaders are also used by people with reading disabilities who will want to look at videos and images. We did not have consensus that this is a user agent issue or whether it is a responsibility of the screenreader to communicate back to the browser. We did have consensus that @postpone makes a page dynamic, and therefore the user agent must keep the assistive technology informed of dynamic changes. The ARIA language has features for that purpose. As currently written, this behavior of @postpone would require communication from the screenreader to the user agent, and we are not clear how that would work. 3) In section 4.3 @postpone: If there were text material in a postponed iframe (or other resource), would that material be available to text search? Please clarify that behavior. Our concern is that if a user searches for a string in a page which includes a @postponed iframe, the search will not find content in the iframe because it has not yet been loaded. People who navigate by lists of links, or lists of headers would usually want to access all of the links on the page (including the postponed iframe), but we can imagine use cases where they would not be appropriate. 4) in Section 4.3 Postpone: It should explicitly state that print overrides postponed. @postpone uses the term "User Agent's interpretation of the document's viewport", if user loads a page and hits PRINT, then the viewport changes to the entire document, and all resources need to be downloaded, for the printing viewport. 5) We recommend that it be explicitly stated in the introduction that user agents give the user the ability to disable @lazyload and @postpone to accommodate assistive technology that may block any content that is not available on pageload. [UAWG: Do we still want to say this? I did not catch what the consensus was here.] 6) In Section 4.4 the "resource-priorities" CSS attribute: a) [minor] lazy-load in CSS and @lazyload in HTML are spelled differently. This adds to the cognitive load and increases errors b) It needs to be explicitly stated that the CSS lazy-load and postpone need to be able to be overridden by a user stylesheet. If you would like to discuss any of these issues further, UAWG would be available for email exchange, a joint phone call, or individuals working together. Regards, Jim Allan, Co-Chair Kelly Ford, Co-Chair Jeanne Spellman, Staff Contact on behalf of the UAWG
Received on Thursday, 16 January 2014 20:04:40 UTC