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.
- 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.
- 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
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.
- 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
- 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".
- 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
- 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
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
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
- Formulate techniques for explicit links to the most important parts of
- 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
- Create new baseline-free wording for "Documents that have five or
more section headings and are presented as a single delivery unit include
of contents with links to important sections of the document. " Issue
- Create new baseline-free wording for "There is more than one
way to locate the content of each delivery unit, including but not limited
groups, a site map, site search or other navigation mechanism.". Issue
- Explore impact of not setting a baseline for 2.4 L3 SC 5 & 6.