2.4 Proposal - changes and rationale

New success criteria

• Added new level 1 success criterion: "For each reference to another delivery unit, a title or description of that delivery unit can be programatically determined". This would apply to links (either by using clear link text and/or using the title-attribute), title-attributes for frames, etc. I chose to use the term "delivery unit" to avoid requiring titles for references to URIs like CSS-files.

New definition

• Added definition for document "a writing that contains information". Source: dictionary.com, wikipedia. I decided to include a definition instead of a note because it keeps the SC easier to read.

Changed levels

• Moved SC about reading order to level 1.
  I chose not to delete this SC because I do not feel saying it is covered under "Structures and relationships within the content can be programmatically determined" is stretching what we mean by that.
  I put this SC at level 1 instead of level 3 because I think it will not be hard to meet in the real world and is reasonably applicable to all websites without infringing the freedom of speech since it can be done without effecting the (visual) presentation. Most real world scenarios will be either cases where the defined sequence of the content is logical or will use be technologies where there is no meaningful sequence (which would meet this SC by default). However, if the provided sequence is not meaningful is very harmful for accessibility so it needs to be addressed in the guidelines.

Changed wording

• New wording for 2.4 L3 SC2: "Blocks of repeated material are implemented so that they can be bypassed by people who use assistive technology or who navigate via keyboard or keyboard interface."
• Changed 7 instances of the word "header" into "heading" because they were used interchangably without reason. I chose Heading because it is the term used in the HTML specification as well and because "header" is ambiguous: it can either mean the top part of a page or a title above a piece of text.
• Changed wording of the note for level 1 SC 1 because it said that conforming to level 1 SC 1 of 1.3 would satisfy level 1 of guideline 2.4. Since we now have more than 1 level 1 SC in 2.4, this is no longer true. Changed the wording to "... also addresses this success criterion" instead of "also addresses this guideline at level 1".

Examples

• Added example of logical reading order (from general techniques) as John Slatin suggested. This addresses part of issue 946.
• Added example about different ways to find content. This addresses issue 1390.
• Expanded example about scalable image with structure to make it clearer that you need a technology that supports doing that and that this is about web content. Also changed the example from bike to map so it makes more sense to use such a technology. This addresses issue 510 and 1392.
• Changed example about audio presentation. This addresses issue 948.
• Deleted the word 'subtle' from example 1 to address issue 676

Decided to keep "as is"

• No new SC for "a sitemap is needed if you cannot access every page of the site from every other page of the site" because it's not applicable to each technology and sitemap is already covered by L2 SC2.
• No new SC that requires explicit links to the most important parts of the content as this can be solved in techniques.
• No new SC to identify 'necessary' links because that's not reliably testable.
• The level 1 SC "Structures and relationships within the content can be programmatically determined." has been retained in 2.4, even though it overlaps with 1.3. The reason for this is that semantic markup is the foundation upon which much of 2.4 is built. Removing this SC would mean removing many of the benefits of 2.4 which have no place in 1.3 either.
  Also, the requirement to indicate structure and relationships has two faces: one is perceivability, because different people can choose different modes of display while retaining the structure, and the other is operability, because having structure can help users orienting and navigating.
  Also, the techniques for the 2.4 instance of this SC can focus on the structure that benefits findability, navigation and orientation, while the techniques for the 1.3 instance of this SC can focus on the structure that helps in perceiving the content.
• Decided to keep the example about jumping from header to header because it's very recognizable for developers even though it's not applicable to all technologies. In my view, not all examples have to work for all technologies. Chosing examples from a wide range of technologies only helps the users of our guidelines to understand them. The other examples are chosen with CSS (aural stylesheet) and SVG (scalable map) in mind, so why not have one with HTML in mind?
• I have decided against a generic version of 'text is divided into paragraphs' and 'documents are divided into hierarchical sections and subsections'. (Issue 1137) The problem with this is that it's hard to make it testable. What I would like to say is "Split large pieces of content into more managable pieces" but both "large" and "managable" are not reliably testable. I do not think it's possible to create a testable generic version, so all we can do is include SC for cases where it is possible to come up with a testable wording like 'text is divided into paragraphs' and 'documents are divided into hierarchical sections and subsections'.

Remaining action items

Techniques

• Formulate techniques for explicit links to the most important parts of the content
• Link techniques for frame titles and clear link text to the new SC to require a title or description for referenced delivery units.
• Create techniques and/or guide text for creating tables of content and/or sitemaps that include information about presentation modes (issue 955)
• Create techniques for effective use of metadata

Wording

• Create new baseline-free wording for "Documents that have five or more section headings and are presented as a single delivery unit include a table of contents with links to important sections of the document. " Issue 1503.
• Create new baseline-free wording for "There is more than one way to locate the content of each delivery unit, including but not limited to link groups, a site map, site search or other navigation mechanism.". Issue 1504.

Misc.

• Explore impact of not setting a baseline for 2.4 L3 SC 5 & 6. Issue 1508