SWAD-Europe Deliverable 9.1: Visualisation and
Accessibility - initial analysis
- Project name:
- Semantic Web Advanced Development for Europe (SWAD-Europe)
- Project Number:
- IST-2001-34732
- Workpackage name:
- 9 Visualisation and Accessibility
- Workpackage description:
- http://www.w3.org/2001/sw/Europe/plan/workpackages/live/esw-wp-9.html
- Deliverable title:
- 9.1 Visualisation and Accessibility
- URI:
- http://www.w3.org/2001/sw/Europe/reports/w3c_note_sw_accessibility
- Authors:
- Charles McCathieNevile, W3C
- Abstract:
- This report surveys areas in which the Semantic Web may be able to
support increased accessibility of the Web for people with
disabilities. It is a position paper which will list ideas that will be
developed to the point where they can be offered to the Web
Accessibility Initiative.
- Status:
Completed report: 2003-02-01.
This document has not been formally reviewed by the Web Accessibilty
Initiative (WAI). It does not reflect a consensus, and techniques
outlined in this document may introduce new accessibility problems. It
is conceived as a "position paper". A further report to be produced as
part of Work
package 9: Visualisation and Accessibility will document the
response of working groups within WAI to the proposals in this report.
When that new report is published (expected in January 2004) readers
should refer to that instead, and this report will be updated to
reflect the availability of the new document.
Comments on this document are welcome and should be sent to the public-esw@w3.org list, archived at
http://lists.w3.org/Archives/Public/public-esw/.
General discussion of accessibility issues should take place on the W3C
WAI Interest Group list w3c-wai-ig@w3.org, archived at http://lists.w3.org/Archives/Public/w3c-wai-ig/.
Further information on the Web Accessibility
Initiative and further resources on Web accessibility for people
with disabilities are available at http://www.w3.org/WAI
Contents
- Introduction
- Background
- Guidelines - Web Content Accessibility
Guidelines
- Guidelines - Authoring Tool Accessibility
Guidelines
- Guidelines - User Agent Accessibility
Guidelines
- Guidelines - XML Accessibility Guidelines
- Themes
- Implementation
- Future Work
- References
This report is part of SWAD-Europe Work package 9:
Visualisation and Accessibility.
For those in a hurry: go straight to the theme summary
section
This report outlines some preliminary suggestions for ways in which the
Semantic Web may further the goals of the Web Accessibility Initiative (WAI)
in making the Web accessible to all people, regardless of disability. It is
primarily focused on four of WAI's 5 areas of work:
- Guidelines
- WAI produces four Guidelines specifications:
- Web Content Accessibility Guidelines [WCAG1, WCAG2]
- This specification outlines requirements for content to ensure
that it is as accessible as possible to all people.
- Authoring Tool Accessibility Guidelines [ATAG1, ATAG2]
- This specifiation outlines requirements for tools used to
produce Web Content, to ensure that they make it possible for all
people to produce content for the Web, and to ensure that tools
support the creation of content that is accessible (meets the
requirements of WCAG), even if the author does not have any prior
knowledge of accessibility requirements. ATAG 1.0 was published
as a W3C Recommendation on 2 February 2000. Work is underway on
ATAG 2.0, which is expected to clarify some minor issues and
align with WCAG 2.0.
- User Agent Accessibility Guidelines [UAAG]
- This specification outlines requirements for user agents such
as Web browsers, Multimedia players and plug-ins, to ensure that
they can be used to provide the best possible access to Web
content for people regardless of disability. UAAG 1.0 was
published as a W3C Recommendation on 17 December 2002.
- XML Accessibility Guidelines [XAG]
- This draft specification outlines requirements for new markup
languages to ensure that it is possible to create and use content
written in those languages regardless of disability. This is a
W3C Working draft.
- Tools
- The Evaluation and Repair Tools working group coordinates development
of tools designed to improve accessibility. There are two major focuses
- evaluation of the accessibility of Web Content, and improving its
accessibility both as an author and as a user.
- Format Review
- The Protocols and Formats working group of WAI works to ensure that
W3C specifications support accessibility to the greatest extent
possible.
- Education and Outreach
- The Education and Outreach working group produces documents,
educational materials, and develops and coordinates presentations
designed to help people understand why and how to improve the
accessibility of their Web Content or Web-related tools.
The fifth area of WAI work is providing some coordination for Research and
Development in areas related to, or beneficial to accessibility. This work
package has provided some input to that work, and this report may be used as
further input, but it is beyond the general scope of this report to provide
inut specifically to that group.
This report is structured as a list of Semantic Web technologies that
might provide useful techniques for the work outlined above. The suggestions
are listed according to the area for which they relevant, following the order
above. In the case of specifications which have a current Recommendation and
a version 2.0 working draft (WCAG and ATAG) suggestions are given for the
current Recommendation.
Since many techniques outlined are relevant to several areas, they are
named each time, with a cross reference to a single explanation of the
technique. Where appropriate, external documents explaining the techinque may
be referred to or linked to as the primary explanation.
The Web can be understood as an information warehouse, with various types
of browsers and user agents used to access it. It is also the host for a
number of services - the same user agents provide the "front desk" for
interacting with the services available. As the Web has grown in popularity
many services are only available, or primarily available, online. For people
with disabilities this has offered the opportunity to use services which they
could not use in the "physical" world, but it has also produced new problems
of access. These are discussed more fully in documents produced by the Web
Accessibility Initiative (WAI) of W3C and in other areas.
Many of the problems introduced appear to be opportunities for useful
application of the Semantic Web. The following proposals have been put
together by people working in the SWAD-E project, and have not been endorsed
as appropriate or useful solutions. Further collaboration between WAI and the
SWAD-E project will identify which of the techniques suggested below merit
further development and implementation.
The Web Content Accessibility Guidelines 1.0 was published as a W3C
Recommendation on 5 May 1999. It consists of 65 checkpoints divided into
three levels of priority and 14 general guidelines. These are the fundamental
requirements for user agents to be able to present content in different ways
to meet the needs of different users, and they are the requirements for the
content that authoring tools need to guide authors to produce.
Work is now underway on WCG 2.0 [WCAG2] which will
clarify the way the Guidelines apply to a wide range of Web Content. It is
expected that only a few requirements will change, as a result of changes in
the state of the art since the publication of WCAG 1.0. There is a mapping
published by the working group between WCAG 1.0 and WCAG 2.0 drafts. The
following is based on WCAG 1.0. New requirements introduced by WCAG 2.0 (for
example for newer technologies) will be discussed as part of collaboration
with the Working Group. The focus of this work will be to identify techniques
that justify and require further development in deliverable 9.2 of the
SWAD-Europe project.
WCAG 1.0
Checkpoint 1.1 Provide a text
equivalent for every non-text element
- Annotea associated alternatives
- Annotea is an RDF-based protocol that allows for third-party
annotations of any Web Resource.
- Jpeg embedded alternatives - RDFPic, EXIF, XMP
- RDFPic allows authors to embed data about the picture within the
picture itself. This can include a description of the picture, and
functions for which the picture is suitable.
- SVG Overlay - image annotation, Patrick Roth's work
- The SVG format allows for multiple levels of description. It also
allows for a bitmapped image (jpeg or png formats are required by the
specification, and gif images are commonly understood by tools) to be
included in the image. This provides the possibility of overlaying an
image with small invisible regions which can be navigated, and which
provide descriptions of parts of the image.
- SVG Metadata - network example
- The SVG format allows information about an image or part(s) of an
image to be directly embedded within the metadata element.
Checkpoint
1.2Provide redundant text links for each active region of a server-side
image map.
Checkpoint
1.3 Until user agents can automatically read aloud the text equivalent of
a visual track, provide an auditory description of the important information
of the visual track of a multimedia presentation.
Checkpoint
1.4 For any time-based multimedia presentation (e.g., a movie or
animation), synchronize equivalent alternatives (e.g., captions or auditory
descriptions of the visual track) with the presentation.
- SMIL/SVG/Annotea
- Because the Annotea system uses URI references including Xpointers,
and W3C multimedia formats such as SMIL and timed-text use XML as their
basis, it is possible to make annotations which refer to particular
timestamps. In addition, if the annotea context property allows for RDF
content very powerful mechanisms can be made available for referring to
a part of a time-based presentation. One approach to this is to create
a vocabulary to deal with timing that has a clear mapping to SMIL,
similar to Jim Ley's vocabulary for regions of an image which maps to
SVG [JImAnno]].
- Visual versions of text or audio systems
- Languages such as timed text (under development) and VoiceXML specify
mechanisms for audio or text-based interface design. However it is
possible, by annotating the components of a VoiceXML application or a
timed text track, to provide alternatives in the form of graphic
symbols or sign-language captions which could be used by user agents to
represent the application using these formats.
Checkpoint
1.5 Until user agents render text equivalents for client-side image map
links, provide redundant text links for each active region of a client-side
image map
Checkpoint
2.1 Ensure that all information conveyed with color is also available
without color, for example from context or markup.
Checkpoint
2.2 Ensure that foreground and background color combinations provide
sufficient contrast when viewed by someone having color deficits or when
viewed on a black and white screen. [Priority 2 for images, Priority 3 for
text].
Checkpoint 3.1
When an appropriate markup language exists, use markup rather than images to
convey information.
Annotating images / closed binary formats with pointers to equivalent
pieces in more open formats can allow for CC/PP solutions to select provide
the best option a user can handle. See also 6.3, 8.1, etc
Checkpoint
3.2 Create documents that validate to published formal grammars.
Checkpoint
3.3 Use style sheets to control layout and presentation.
Checkpoint
3.4 Use relative rather than absolute units in markup language attribute
values and style sheet property values
Checkpoint
3.5 Use header elements to convey document structure and use them
according to specification.
See also XAG checkpoint 3.2 - documenting navigable structures, WCAG
checkpoint 9.4 provide "tab" order
Checkpoint
3.6 Mark up lists and list items properly.
Checkpoint 3.7 Mark
up quotations. Do not use quotation markup for formatting effects such as
indentation
Checkpoint
4.1 Clearly identify changes in the natural language of a document's text
and any text equivalents (e.g., captions)
- Annotating "alt-text"
- One of the most common methods of putting text alternatives on the
web is via HTML's alt attribute. However HTML does not provide a
mechanism for identifying the language of particular attributes, let
alone parts of an attriute value. This can be achieved through the use
of annotation systems such as annotea or information included within a
document.
Checkpoint 4.2
Specify the expansion of each abbreviation or acronym in a document where it
first occurs
- ILS approach
- The use of glossaries to provide possible expansions, combined with
the ability to compare the possible entries against the domain of a
document to "guess" the most probable, can help. It is likely to be
more useful in an authoring tool, where the author can ensure that a
particular explansion is the corect one.
Checkpoint
4.3 Identify the primary natural language of a document.
Checkpoint
5.1 For data tables, identify row and column headers.
Checkpoint
5.2 For data tables that have two or more logical levels of row or column
headers, use markup to associate data cells and header cells.
Checkpoint
5.3 Do not use tables for layout unless the table makes sense when
linearized. Otherwise, if the table does not make sense, provide an
alternative equivalent (which may be a linearized version)
Checkpoint
5.4 If a table is used for layout, do not use any structural markup for
the purpose of visual formatting.
- EARL
- Annotating a table as a visual layout table can help evaluation
tools. It can also be used to identify things which could be replaced
in a service that convers layout to a more appropriate format - like
tablin [TABLIN] but poducing CSS or SVG.
Checkpoint
5.5 Provide summaries for tables.
Checkpoint
5.6 Provide abbreviations for header labels.
Checkpoint
6.1 Organize documents so they may be read without style sheets. For
example, when an HTML document is rendered without associated style sheets,
it must still be possible to read the document.
Checkpoint
6.2 Ensure that equivalents for dynamic content are updated when the
dynamic content changes.
Checkpoint 6.3
Ensure that pages are usable when scripts, applets, or other programmatic
objects are turned off or not supported. If this is not possible, provide
equivalent information on an alternative accessible page.
- Semantically described services
- The use of Semantically rich descriptions for services on the Web can
include machine-processable information about alternative versions of a
service that may be appropriate to a particular delivery context. This
can allow searching for more accessible versions of a script or applet
being used, or directing useers directly to an laternative.
Checkpoint
6.4 For scripts and applets, ensure that event handlers are input
device-independent
Checkpoint
6.5 Ensure that dynamic content is accessible or provide an alternative
presentation or page.
- Annotation of controls
- For interactive elements, knowing what a control does is important,
but too much detail in a page can make it harder to use. Some
languages, such as Xforms, provide for contect-sensitive help, but this
can also be added through Annotea or similar systems where it is not
already available.
Checkpoint
7.1 Until user agents allow users to control flickering, avoid causing
the screen to flicker.
Checkpoint
7.2 Until user agents allow users to control blinking, avoid causing
content to blink (i.e., change presentation at a regular rate, such as
turning on and off)
Checkpoint
7.3 Until user agents allow users to freeze moving content, avoid
movement in pages
Checkpoint
7.4 Until user agents provide the ability to stop the refresh, do not
create periodically auto-refreshing pages.
Checkpoint
7.5 Until user agents provide the ability to stop auto-redirect, do not
use markup to redirect pages automatically. Instead, configure the server to
perform redirects.
Checkpoint
8.1 Make programmatic elements such as scripts and applets directly
accessible or compatible with assistive technologies.
Checkpoint
9.1 Provide client-side image maps instead of server-side image maps
except where the regions cannot be defined with an available geometric
shape.
Checkpoint
9.2 Ensure that any element that has its own interface can be operated in
a device-independent manner.
Checkpoint
9.3 For scripts, specify logical event handlers rather than
device-dependent event handlers.
Checkpoint 9.4
Create a logical tab order through links, form controls, and objects.
Checkpoint
9.5 Provide keyboard shortcuts to important links (including those in
client-side image maps), form controls, and groups of form controls.
- Site Mapping
- Automatically generated site maps can be used to identify resources
that are linked to from many parts of the site as good candidates for a
shortcut.
Checkpoint
10.1 Until user agents allow users to turn off spawned windows, do not
cause pop-ups or other windows to appear and do not change the current window
without informing the user.
Checkpoint
10.2 Until user agents support explicit associations between labels and
form controls, for all form controls with implicitly associated labels,
ensure that the label is properly positioned
Checkpoint
10.3 Until user agents (including assistive technologies) render
side-by-side text correctly, provide a linear text alternative (on the
current page or some other) for all tables that lay out text in
parallel, word-wrapped columns.
Checkpoint
10.4 Until user agents handle empty controls correctly, include default,
place-holding characters in edit boxes and text areas.
Checkpoint
10.5 Until user agents (including assistive technologies) render adjacent
links distinctly, include non-link, printable characters (surrounded by
spaces) between adjacent links.
Checkpoint
11.1 Use W3C technologies when they are available and appropriate for a
task and use the latest versions when supported
- TR Automation
- The availability of an RDF version of the W3C's specifications
catalogue allows searching for newer versions of specifications than
the one proposed for use, and in some cases automatic updating services
are possible.
- Schema Annotation
- The use of annotation to decsribe the purpose of various modules (see
also XAG checkpoint 2.9) allows searching
for appropriate modules for a particular task.
Checkpoint
11.2 Avoid deprecated features of W3C technologies.
- Schema Annotation
- Annotating elements of schemas which are new, obsolete or deprecated,
or render sections of earlier specifications obsolete would allow for
some automatic testing of this checkpoint.
Checkpoint
11.3 Provide information so that users may receive documents according to
their preferences (e.g., language, content type, etc.)
- CC/PP
- This is a framework designed to allow servers to communicate with a
user's client and determine their needs and preferences, then attempt
to provide the most appropriate version of content according to those
needs or preferences
- EARL
- This allows descriptions of how particular pieces of content meet
requirements. It can be used in a system which dynamically generates
content in order to select a version of some information which meets
some specified requirements - for example in conjunction with
CC/PP.
Checkpoint 11.4
If, after best efforts, you cannot create an accessible page, provide a link
to an alternative page that uses W3C technologies, is accessible, has
equivalent information (or functionality), and is updated as often as the
inaccessible (original) page.
Checkpoint
12.1 Title each frame to facilitate frame identification and
navigation.
Checkpoint
12.2 Describe the purpose of frames and how frames relate to each other
if it is not obvious by frame titles alone.
- Site Mapping
- The navigation paths and combinations of frames - which links can
lead to which collections of framesets, and therefore what are the
"obvious" pathways could be developed by extending automated
site-mapping systems to be aware of framesets.
Checkpoint
12.3 Divide large blocks of information into more manageable groups where
natural and appropriate.
Checkpoint
12.4 Associate labels explicitly with their controls.
- Extending HTML
- In HTML, form controls can be explicitly associated with a label, but
this is a one to one mapping. There are mechanisms in certain cases for
associating a label with a group of controls (e.g. fieldset). But it is
not possible, for example, to associate an HTML link explicitly with a
particular part of its immediate context, nor to associate a group of
controls with two or more labels in the general case. (It is commonly
achieved by using table markup to associate headers as labels, but this
is not always appropriate).
Checkpoint
13.1 Clearly identify the target of each link.
- RDF about
- RDF information describing a particular URI reference can be used to
provide information about a link target which is not directly included
in a page. For example having multi-lingual titles or descriptions of
the resource linked to, including visual representations such as sign
language. These can be used in systems such as IRC with the annotea
protocol, or presented as (possibly visual) tool-tips by advanced user
agents.
Checkpoint
13.2 Provide metadata to add semantic information to pages and sites.
In particular CC/PP and EARL type approaches.
Checkpoint
13.3 Provide information about the general layout of a site (e.g., a site
map or table of contents)
Site mapping
Checkpoint
13.4 Use navigation mechanisms in a consistent manner.
Site mapping
Checkpoint 13.5
Provide navigation bars to highlight and give access to the navigation
mechanism.
Site mapping
Checkpoint
13.6 Group related links, identify the group (for user agents), and,
until user agents do so, provide a way to bypass the group.
Checkpoint 13.7
If search functions are provided, enable different types of searches for
different skill levels and preferences.
- Semantically enhanced searches
- Plain text searching in a page is a function normally provided by a
browser. There are commercially available and free systems for
providing plain-text indexing of a site. These systems can be augmented
with Semantic Web-based searching to allow searches for specific types
of information, etc.
- Site Mapping
- Tools can crawl sites and determine the graph defined by links
between various parts of the site. When collected as RDF this
information can then be used with RDF visualisation tools such as
GraphViz or RDF Author to provide a visual map of the site.
Checkpoint
13.8 Place distinguishing information at the beginning of headings,
paragraphs, lists, etc.
Checkpoint
13.9 Provide information about document collections (i.e., documents
comprising multiple pages.).
- Cataloguing metadata
- The use of cataloguing metadata can allow the automatic generation of
the information required to meet this checkpoint.
Checkpoint
13.10 Provide a means to skip over multi-line ASCII art
Checkpoint
14.1 Use the clearest and simplest language appropriate for a site's
content.
See ILS method
Checkpoint 14.2
Supplement text with graphic or auditory presentations where they will
facilitate comprehension of the page.
See 1.1 for annotations, and ILS method
Checkpoint
14.3 Create a style of presentation that is consistent across pages.
- Site mapping
- Using RDF to collect information about the pages in a particular
collection can provide a list of pages to check for a tool that
compares the presentation information (style sheets used, basic
structure of pages, etc).
ATAG 1
Checkpoint
1.1 Ensure that the author can produce accessible content in the
markup language(s) supported by the tool.
- Image annotation
- In developing real-time interactive image editing tools, image
annotation can provide the ability to build images using previously
described components, or to add descriptions as new parts of images are
added.
Checkpoint
1.2 Ensure that the tool preserves all accessibility information
during authoring, transformations, and conversions.
- Annotea
- Some accessibility information cannot readily be encoded in some
formats. One technique for maintaining information about a particular
part of a document is to store it as an annotea annotation
- Images
- In most image formats there is a method for storing comments, which
can be used to store various types of accessibility information as RDF
(see also ideas for WCAG checkpoint 1.1). Being able to extract such
information can be helpful
- Add information back
- Where accessibility information has been stored as an external
annotation, it may be possible to include that information directly in
a resource.
Checkpoint
1.3 Ensure that when the tool automatically generates markup it conforms
to the W3C's Web Content
Accessibility Guidelines 1.0 [WCAG1].
Checkpoint
1.4 Ensure that templates provided by the tool conform to the Web
Content Accessibility Guidelines 1.0 [WCAG1].
- EARL
- Tools can use EARL reports to ensure meeting this checkpoint while
making online content available as a template.
Checkpoint
2.1 Use the latest versions of W3C Recommendations when they
are available and appropriate for a task.
- TR Automation
- The W3C's technical reports list is now available as RDF, including
information about the history of documents. If a given format is
selected this can be used to find the latest available version.
Checkpoint
2.2 Ensure that the tool automatically generates valid markup.
Checkpoint
2.3 If markup produced by the tool does not conform to W3C
specifications, inform the author.
Checkpoint
3.1 Prompt the author to provide equivalent alternative information
(e.g., captions, auditory descriptions, and collated text transcripts for
video).
See also ATAG checkpoint 3.5, WCAG
checkpoint 1.1
- Prompting help
- Where there are annotations about alternative versions of a media
object these can be used to propose a value to the author.
- Glossary help
- RDF-based dictionary services can be used to offer expansions for
acronyms. Extensions of this functionality can provide likely contexts,
or rank alternatives by likelihood according to contextual
information.
Checkpoint
3.2 Help the author create structured content and separate
information from its presentation.
Checkpoint
3.3 Ensure that prepackaged content conforms to the Web Content
Accessibility Guidelines 1.0 [WCAG1].
Checkpoint
3.4 Do not automatically generate equivalent alternatives. Do not
reuse previously authored alternatives without author confirmation, except
when the function is known with certainty.
- Image annotation
- LIFT for Dreamweaver (and other tools) include a functionality for
classifying images. This can be used to determine that certain images
are spacers, and a null alternative is appropriate.
Checkpoint
3.5 Provide functionality for managing, editing, and reusing
alternative equivalents for multimedia objects.
- Image Annotation
- See for example the Amaya SVG library as a way of implementing this
in an authoring tool. The LIFT for Dreamweaver tool also collects
images according to their type.
Checkpoint
4.1 Check for and inform the author of accessibility problems.
- EARL
- The use of EARL to record accessibility problems found can be
integrated with information from the author, to provide a more accurate
report. An example of this is implemented in the open-source tool
WAI-Nu, developed in part with support from the SWAD-Europe
project.
Checkpoint
4.2 Assist authors in correcting accessibility problems.
- Extending EARL.
- Extending EARL tools to identify the particular way in which a test
is failed would allow tools to track information on repairs that can be
applied for that class of failure. This could be used to integrate
different tools or tool modules into a workflow to produce a result
benefitting from the syngergies available.
Checkpoint
4.3 Allow the author to preserve markup not recognized by the
tool.
- Round-tripping
- A tool may need to change unrecognised markup as it makes changes to
a document - for example to maintain code validity. Storing information
about the changes made can be used to allow the author to reconstruct
the original code, or for a different tool that understands the markup
to do so. A simple vocabulary constructed around the diff utility would
seem a good candidate strategy.
Checkpoint
4.4 Provide the author with a summary of the document's
accessibility status.
- EARL
- This can be used to provide reporting of current status in an
authoring tool. (This technique is demonstrated in tools such as
AccVerify or LIFT which integrate with authoring tools).
Checkpoint
4.5 Allow the author to transform presentation markup that is
misused to convey structure into structural markup, and to transform
presentation markup used for style into style sheets.
Checkpoint
5.1 Ensure that functionality related to accessible authoring
practices is naturally integrated into the overall look and feel of the
tool.
- Reading XAG
- The XAG requirements for documented techniques for accessibility may
give rise to RDF or RDF-compatible information that can be presented to
the author when using a particular feature of a tool or language. See
also ATAG Checkpoint
6.2
Checkpoint
5.2 Ensure that accessible authoring practices supporting Web
Content Accessibility Guidelines 1.0 [WCAG1] Priority 1 checkpoints are among
the most obvious and easily initiated by the author.
Checkpoint
6.1 Document all features that promote the production of accessible
content.
Checkpoint
6.2 Ensure that creating accessible content is a naturally
integrated part of the documentation, including examples.
Checkpoint
6.3 In a dedicated section, document all features of the tool that
promote the production of accessible content.
- Document Metadata
- If the help documentation includes appropriate metadata, features
that promote the production of accessible content can be collected
together in a single view as required. This is particularly relevant to
Content Management Systems which are self-describing.
Checkpoint
7.1 Use all applicable operating system and accessibility standards
and conventions.
Checkpoint
7.2 Allow the author to change the presentation within editing views
without affecting the document markup.
Checkpoint
7.3 Allow the author to edit all properties of each element and
object in an accessible fashion.
Checkpoint
7.4 Ensure that the editing view allows navigation via the structure
of the document in an accessible fashion.
Checkpoint
7.5 Enable editing of the structure of the document in an accessible
fashion.
- Implementing XAG
- for formats which are lacking in important structure, RDF can be used
top describe the underlying structure of the document. This approach is
essentially that used in "external markup" systems.
Checkpoint
7.6 Allow the author to search within editing views.
The User Agent Accessibility Guidelines describe requirements for "user
agents" - browsers, media players and plugins, and user interfaces in
general. This includes "web applications" - intereactive web content, which
functions in some way as a user agent. The User Agent Accessibility
Guidelines 1.0 became a W3C recommendation on 21 December 2002.
The fact that some user agents, such as the Mozilla browser and the Amaya
editor/browser already incorporate an RDF parser (and in Amaya's case an
Annotea user interface as a default, with one also available for Mozilla and
other user agents) suggests that many of the following techniques could be
relatively easay to implement as strategies to reach conformance with the
requirements of these guidelines.
Guideline 1. Support input and output
device-independence
- Describing alternative services
- For content with its own interface components, such as a java applet,
it is possible to use RDF or RDF-compatible languages to describe the
service, and thus to search for an alternative service which has the
same functions but which is accessible.
Conformance profile labels: Events
1. Allow the user to activate, through keyboard input alone, all input
device event handlers that are explicitly associated with the element
designated by the content focus.
2. In order to satisfy provision one of this checkpoint, the user must be
able to activate as a group all event handlers of the same input device event
type. For example, if there are 10 handlers associated with the onmousedown
event type, the user must be able to activate the entire group of 10 through
keyboard input alone, and must not be required to activate each handler
separately.
- Image Annotation
- In Web applications annotations can be used to describe objects which
are part of an interface. The development of specifications such as XUL
and the CSS 3 Basic User Intereface model points to this being a trend
in development.
- Semantically described services
- Can be used, with the ability to describe alternatives available
according to different renderings.
Guideline 2. Ensure user access to all content
Checkpoint
2.1 Render content according to specification.
1. Render content according to format specification (e.g., for a markup
language or style sheet language).
1. For content authored in text formats, provide a view of the text
source.
Conformance detail: For all content
1. Allow configuration to provide access to each piece of unrendered
conditional content "C".
2. When a specification does not explain how to provide access to this
content, do so as follows:
If C is a summary, title, alternative, description, or expansion of
another piece of content D, provide access through at least one of the
following mechanisms:
(1a) render C in place of D;
(2a) render C in addition to D;
(3a) provide access to C by allowing the user to query D. In this case,
the user agent must also alert the user, on a per-element basis, to the
existence of C (so that the user knows to query D); and
(4a) allow the user to follow a link to C from the context of D.
Otherwise, provide access to C through at least one of the following
mechanisms:
(1b) render a placeholder for C, and allow the user to view the original
author-supplied content associated with each placeholder;
(2b) provide access to C by query (e.g., allow the user to query an
element for its attributes). In this case, the user agent must also alert the
user, on a per-element basis, to the existence of C; and
(3b) allow the user to follow a link in context to C.
Checkpoint
2.4 Allow time-independent interaction.
1. For rendered content where user input is only possible within a finite
time interval controlled by the user agent, allow configuration to provide a
view where user interaction is time-independent.
Checkpoint
2.5 Make captions, transcripts, audio descriptions available.
Conformance detail: For all content
1. Allow configuration or control to render text transcripts, collated
text transcripts, captions, and audio descriptions in content at the same
time as the associated audio tracks and visual tracks.
Checkpoint
2.6 Respect synchronization cues.
Conformance profile labels: Video, Audio
1. Respect synchronization cues (e.g., in markup) during rendering.
- Image Annotation
- Image annotation techniques above may mean that some data about
images (such as a description, or alternative content used for the same
image in a different document) is available to the user agent
Conformance detail: For all content
1. Allow at least two configurations for when the user agent recognizes
that conditional content required by the format specification is present but
empty content:
generate no repair text.
generate repair as described in checkpoint 2.7.
Checkpoint
2.9 Render conditional content automatically.
Conformance detail: For all content
1. Allow configuration to render all conditional content automatically.
2. As part of satisfying provision one of this checkpoint, provide access
according to specification, or where unspecified, by applying one of the
techniques 1a, 2a, or 1b defined in provision two of checkpoint 2.3.
Checkpoint
2.10 Don't render text in unsupported writing systems.
1. For graphical user agents, allow configuration not to render text in
unsupported scripts (i.e., writing systems) when that text would otherwise be
rendered.
2. When configured per provision one of this checkpoint, indicate to the
user in context that author-supplied content has not been rendered due to
lack of support for a writing system.
Guideline 3. Allow configuration not to render some
content that may reduce accessibility
Conformance profile labels: Image
1. Allow configuration not to render background image content.
Checkpoint
3.2 Toggle audio, video, animated images.
Conformance profile labels: Animation, Video, Audio
1. Allow configuration not to render audio, video, or animated image
content, except on explicit user request.
Checkpoint
3.3 Toggle animated or blinking text.
Conformance profile labels: VisualText
1. Allow configuration to render animated or blinking text content as
motionless, unblinking text. Blinking text is text whose visual rendering
alternates between visible and invisible, at any rate of change.
1. Allow configuration not to execute any executable content (e.g.,
scripts and applets).
Checkpoint
3.5 Toggle automatic content retrieval.
1. Allow configuration so that the user agent only retrieves content on
explicit user request.
- Allow configuration not to render image content.
Guideline 4. Ensure user control of rendering
Conformance profile labels: VisualText
1. Allow global configuration of the scale of visually rendered text
content. Preserve distinctions in the size of rendered text as the user
increases or decreases the scale.
2. As part of satisfying provision one of this checkpoint, provide a
configuration option to override rendered text sizes specified by the author
or user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a range
of text sizes to the user that includes at least:
the range offered by the conventional utility available in the operating
environment that allows users to choose the text size (e.g., the font size),
or
if no such utility is available, the range of text sizes supported by the
conventional APIs of the operating environment for drawing text.
Conformance profile labels: VisualText
1. Allow global configuration of the font family of all visually rendered
text content.
2. As part of satisfying provision one of this checkpoint, provide a
configuration option to override font families specified by the author or by
user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a range
of font families to the user that includes at least:
the range offered by the conventional utility available in the operating
environment that allows users to choose the font family, or
if no such utility is available, the range of font families supported by
the conventional APIs of the operating environment for drawing text.
Conformance profile labels: VisualText
1. Allow global configuration of the foreground and background color of
all visually rendered text content.
2. As part of satisfying provision one of this checkpoint, provide a
configuration option to override foreground and background colors specified
by the author or user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a range
of colors to the user that includes at least:
the range offered by the conventional utility available in the operating
environment that allows users to choose colors, or
if no such utility is available, the range of colors supported by the
conventional APIs of the operating environment for specifying colors.
Conformance profile labels: Animation, Audio
1. Allow the user to slow the presentation rate of rendered audio and
animation content (including video and animated images).
2. As part of satisfying provision one of this checkpoint, for a visual
track, provide at least one setting between 40% and 60% of the original
speed.
3. As part of satisfying provision one of this checkpoint, for a
prerecorded audio track including audio-only presentations, provide at least
one setting between 75% and 80% of the original speed.
4. When the user agent allows the user to slow the visual track of a
synchronized multimedia presentation to between 100% and 80% of its original
speed, synchronize the visual and audio tracks (per checkpoint 2.6). Below
80%, the user agent is not required to render the audio track.
Checkpoint
4.5 Start, stop, pause, and navigate multimedia.
- Media Annotation
- Annotation of multimedia such as SMIL can be used to provide
important navigation marks for a media file, as per XAG checkpoint 2.4.
1. For graphical viewports, allow configuration so that captions
synchronized with a visual track in content are not obscured by it.
Conformance detail: For both content and user agent
1. Allow global configuration of the volume of all rendered audio, with an
option to override audio volumes specified by the author or user agent
defaults.
2. As part of satisfying provision one of this checkpoint, allow the user
to choose zero volume (i.e., silent).
Conformance profile labels: Audio
1. Allow independent control of the volumes of rendered audio content
synchronized to play simultaneously.
Checkpoint
4.9 Configure synthesized speech rate.
Conformance profile labels: Speech
1. Allow configuration of the synthesized speech rate, according to the
full range offered by the speech synthesizer.
Checkpoint
4.10 Configure synthesized speech volume.
Conformance profile labels: Speech
1. Allow control of the synthesized speech volume, independent of other
sources of audio.
Checkpoint
4.11 Configure synthesized speech characteristics.
Conformance profile labels: Speech
1. Allow configuration of synthesized speech characteristics according to
the full range of values offered by the speech synthesizer.
Checkpoint
4.12 Specific synthesized speech characteristics.
Conformance profile labels: Speech
1. Allow configuration of synthesized speech pitch. Pitch refers to the
average frequency of the speaking voice.
2. Allow configuration of synthesized speech pitch range. Pitch range
specifies a variation in average frequency.
3. Allow configuration of synthesized speech stress. Stress refers to the
height of "local peaks" in the intonation contour of the voice.
4. Allow configuration of synthesized speech richness. Richness refers to
the richness or brightness of the voice.
Checkpoint
4.13 Configure synthesized speech features.
Conformance profile labels: Speech
1. Provide support for user-defined extensions to the synthesized speech
dictionary.
2. Provide support for spell-out: where text is spelled one character at a
time, or according to language-dependent pronunciation rules.
3. Allow at least two configurations for speaking numerals: one where
numerals are spoken as individual digits, and one where full numbers are
spoken.
4. Allow at least two configurations for speaking punctuation: one where
punctuation is spoken literally, and one where punctuation is rendered as
natural pauses.
1. Allow the user to choose from and apply alternative author style sheets
(such as linked style sheets).
2. Allow the user to choose from and apply at least one user style
sheet.
3. Allow the user to turn off (i.e., ignore) author and user style
sheets.
Guideline 5. Ensure user control of user interface
behavior
Checkpoint
5.1 No automatic content focus change.
1. Allow configuration so that if a viewport opens without explicit user
request, neither its content focus nor its user interface focus automatically
becomes the current focus.
1. For graphical user interfaces, allow configuration so that the viewport
with the current focus remains "on top" of all other viewports with which it
overlaps.
1. Allow configuration so that viewports only open on explicit user
request.
2. When configured per provision one of this checkpoint, instead of
opening a viewport automatically, alert the user and allow the user to open
it with an explicit request (e.g., by confirming a prompt or following a link
generated by the user agent).
3. Allow the user to close viewports.
Checkpoint
5.4 Selection and focus in viewport.
Conformance profile labels: Selection
1. Ensure that when a viewport's selection or content focus changes, it is
at least partially in the viewport after the change.
1. Allow configuration to prompt the user to confirm (or cancel) any form
submission.
Guideline 6. Implement interoperable application
programming interfaces
Checkpoint
6.1 Programmatic access to HTML/XML infoset.
1. Provide programmatic read access to XML content by making available all
of the information items defined by the W3C XML Infoset.
2. Provide programmatic read access to HTML content by making available
all of the following information items defined by the W3C XML Infoset:
Document Information item: children, document element, base URI,
charset
Element Information items: element-type name, children, attributes,
parent
Attribute Information items: attribute-type name, normalized value,
specified, attribute type, references, owner element
Character Information items: character code, parent element
Comment Information items: content, parent
3. If the user can modify the state or value of a piece of HTML or XML
content through the user interface (e.g., by checking a box or editing a text
area), allow programmatic read access to the current state or value, and
allow the same degree of write access programmatically as is available
through the user interface.
Checkpoint
6.2 DOM access to HTML/XML content.
1. Provide access to the content required in checkpoint 6.1 by conforming
to the following modules of the W3C Document Object Model (DOM) Level 2 Core
Specification and exporting bindings for the interfaces they define:
for HTML: the Core module
for XML: the Core and XML modules
2. As part of satisfying provision one of this checkpoint:
In the Java and ECMAScript operating environments, export the normative
bindings specified in the DOM Level 2 Core Specification, or
In other operating environments, the exported bindings (e.g., C++) must be
publicly documented.
Checkpoint
6.3 Programmatic access to non-HTML/XML content.
1. For content other than HTML and XML, provide structured programmatic
read access to content.
2. If the user can modify the state or value of a piece of non-HTML/XML
content through the user interface (e.g., by checking a box or editing a text
area), allow programmatic read access to the current state or value, and
allow the same degree of write access programmatically as is available
through the user interface.
3. As part of satisfying provision one of this checkpoint, implement at
least one API according to this API cascade:
The API is defined by a W3C Recommendation, or the API is publicly
documented and designed to enable interoperability with assistive
technologies.
If no such API is available, or if available APIs do not enable the user
agent to satisfy the requirements,
implement at least one publicly documented API to satisfy the
requirements, and
follow operating environment conventions for the use of input and output
APIs.
Checkpoint
6.4 Programmatic access to information about rendered content.
1. For graphical user agents, make available bounding dimensions and
coordinates of rendered graphical objects. Coordinates must be relative to
the point of origin in the graphical environment (e.g., with respect to the
desktop), not the viewport.
2. For graphical user agents, provide access to the following information
about each piece of rendered text: font family, font size, and foreground and
background colors.
3. As part of satisfying provisions one and two of this checkpoint,
implement at least one API according to the API cascade described in
provision two of checkpoint 6.3.
Checkpoint
6.5 Programmatic operation of user agent user interface.
Conformance detail: For user agent features
1. Provide programmatic read access to user agent user interface controls,
selection, content focus, and user interface focus.
2. If the user can modify the state or value of a user agent user
interface control (e.g., by checking a box or editing a text area), allow
programmatic read access to the current state or value, and allow the same
degree of write access programmatically as is available through the user
interface.
3. As part of satisfying provisions one and two of this checkpoint,
implement at least one API according to the API cascade described in
provision two of checkpoint 6.3.
Checkpoint
6.6 Programmatic notification of changes.
Conformance detail: For both content and user agent
1. Provide programmatic notification of changes to content, states and
values of content, user agent user interface controls, selection, content
focus, and user interface focus.
2. As part of satisfying provision one of this checkpoint, implement at
least one API according to the API cascade of provision two of checkpoint
6.3.
1. Implement APIs for the keyboard as follows:
Follow operating environment conventions.
If no conventions exist, implement publicly documented APIs.
Conformance detail: For both content and user agent
1. For an API implemented to satisfy requirements of this document,
support the character encodings required for that API.
Checkpoint
6.9 DOM access to CSS style sheets.
1. For user agents that implement Cascading Style Sheets (CSS), provide
programmatic access to style sheets by conforming to the CSS module of the
W3C Document Object Model (DOM) Level 2 Style Specification and exporting
bindings for the interfaces it defines.
2. As part of satisfying provision one of this checkpoint:
In the Java and ECMAScript operating environments, export the normative
bindings specified in the CSS module of the DOM Level 2 Style Specification,
or
In other operating environments, the exported bindings (e.g., C++) must be
publicly documented.
Checkpoint
6.10 Timely exchanges through APIs.
Conformance detail: For both content and user agent
1. For APIs implemented to satisfy the requirements of this document,
ensure that programmatic exchanges proceed in a timely manner.
Guideline 7. Observe operating environment
conventions
Checkpoint
7.1 Respect focus and selection conventions.
Conformance profile labels: Selection
1. Follow operating environment conventions that benefit accessibility
when implementing the selection, content focus, and user interface focus.
Checkpoint
7.2 Respect input configuration conventions.
Conformance detail: For user agent features
Conformance profile labels: Selection
1. Ensure that default input configurations of the user agent do not
interfere with operating environment accessibility conventions (e.g., for
keyboard accessibility).
Checkpoint
7.3 Respect operating environment conventions.
Conformance detail: For user agent features
1. Follow operating environment conventions that benefit accessibility. In
particular, follow conventions that benefit accessibility for user interface
design, keyboard configuration, product installation, and documentation.
Checkpoint
7.4 Provide input configuration indications.
Conformance detail: For user agent features
1. Follow operating environment conventions to indicate the input
configuration.
Guideline 8. Implement specifications that benefit
accessibility
Checkpoint
8.1 Implement accessibility features.
- Schema Annotation
- Where schemas carry annotation identifying accessibility features in
the specification this can be more readily tested.
Conformance detail: For all content
1. Use and conform to either
W3C Recommendations when they are available and appropriate for a task,
or
non-W3C specifications that enable the creation of content that conforms
at level A or better to the Web Content Accessibility Guidelines 1.0 [WCAG1].
Guideline 9. Provide navigation mechanisms
- User Profiles
- If user profiles are kept in RDF then it is possible to include
information about the focus point in content using RDF based on the
context property of the Annotea specification.
Checkpoint 9.2
Provide user interface focus.
1. Provide a user interface focus.
1. Allow the user to move the content focus to any enabled element in the
viewport.
2. Allow configuration so that the content focus of a viewport only
changes on explicit user request.
3. If the author has not specified a navigation order, allow at least
forward sequential navigation, in document order, to each element in the set
established by provision one of this checkpoint.
Checkpoint
9.4 Restore viewport state history.
- User Profile
- Maintaining state information in a user profile allows for
portability of this state across sessions or even as the user changes
browser (for example changing environments from a mobile low-bandwidth
browser to a more powerful browser maintained at home with a higher
capacity to adapt content at the client side).
Conformance profile labels: Events
1. Allow configuration so that moving the content focus to or from an
enabled element does not automatically activate any explicitly associated
event handlers of any event type.
Conformance profile labels: Events
1. For the element with content focus, make available the list of input
device event types for which there are event handlers explicitly associated
with the element.
Checkpoint
9.7 Move content focus in reverse
1. Extend the functionality required in provision three of checkpoint 9.3
by allowing the same sequential navigation in reverse document order.
2. As part of satisfying provision one of this checkpoint, the user agent
must not include disabled elements in the navigation order.
Conformance detail: For all rendered content
1. Allow the user to search within rendered text content for a sequence of
characters from the document character set.
2. Allow the user to start a forward search (in document order) from any
selected or focused location in content.
3. When there is a match, do both of the following:
move the viewport so that the matched text content is at least partially
within it, and
allow the user to search for the next instance of the text from the
location of the match.
4. Alert the user when there is no match or after the last match in
content (i.e., prior to starting the search over from the beginning of
content).
5. Provide a case-insensitive search option for text in scripts (i.e.,
writing systems) where case is significant.
- Site Mapping
- Using an RDF vocabulary to identify important navigation points
within a document as well as between them (as discussed for XAG checkpoint 2.4) allows a user agent to
identify the important navigation structures of arbitrary XML
- Schema Annotation
- Providing a mechanism for a user to identify additional annotations,
or to select from those available, can provide the opportunity to
declare obsolete (for a particular user) parts of a schema annotation
identifying important elements for navigation, as per XAG checkpoint 2.4, or make such declarations
for a module described according to XAG
checkpoint 2.9.
Guideline 10. Orient the user
Checkpoint
10.1 Associate table cells and headers.
1. For graphical user agents that render tables, for each table cell,
allow the user to view associated header information.
Checkpoint
10.2 Highlight selection, content focus, enabled elements, visited
links.
Conformance profile labels: Selection
1. Allow global configuration to highlight the following four classes of
information in each viewport: the selection, content focus, enabled elements,
and recently visited links.
2. For graphical user interfaces, as part of satisfying provision one of
this checkpoint, allow at least one configuration where the highlight
mechanisms for the four classes of information:
differ from each other, and
do not rely on rendered text foreground and background colors alone.
3. For graphical user interfaces, as part of satisfying provision one of
this checkpoint, if a highlight mechanism involves text size, font family,
rendered text foreground and background colors, or text decorations, offer at
least the following range of values:
for text size, the range required by provision three of checkpoint 4.1.
for font family, the range required by provision three of checkpoint
4.2.
for text foreground and background colors and decorations, the range
offered by the conventional utility available in the operating environment
for users to choose rendered text colors or decorations (e.g., the standard
font and color dialog box resources supported by the operating system). If no
such utility is available, the range supported by the conventional APIs of
the operating environment for specifying text colors or drawing text.
4. Highlight enabled elements according to the granularity specified in
the format. For example, an HTML user agent rendering a PNG image as part of
a client-side image map is only required to highlight the image as a whole,
not each enabled region. An SVG user agent rendering an SVG image with
embedded graphical links is required to highlight each (enabled) link that
may be rendered independently according to the SVG specification.
Checkpoint
10.3 Single highlight configuration.
- User Profile
- Development of user profiles for various requirements can allow for
common combinations of requirements to be selected with a single
setting.
- Schema Annotation
- The use of schema annotations to identify elements which form part of
an outline view, as per XAG Checkpoint 2.4,
can be used to provide an outline view of a document written conformant
to such a schema.
- Cataloguing metadata
- The availability of Dublin Core or similar cataloguing metadata for
many resources on the Web can be used to provide this information. User
agents can also generate such information for re-use.
1. Highlight the viewport with the current focus (including any frame that
takes current focus).
2. For graphical viewports, as part of satisfying provision one of this
checkpoint, provide at least one highlight mechanism that does not rely on
rendered text foreground and background colors alone (e.g., use a thick
outline).
3. If the techniques used to satisfy provision one of this checkpoint
involve rendered text size, font family, rendered text foreground and
background colors, or text decorations, allow global configuration and offer
same ranges of values required by provision three of checkpoint 10.2.
1. Indicate the viewport's position relative to rendered content (e.g.,
the proportion of an audio or video clip that has been played, or the
proportion of a Web page that has been viewed).
Guideline 11. Allow configuration and customization
Checkpoint
11.1 Current user input configuration.
Conformance detail: For user agent features
1. Provide information to the user about current user preferences for
input configurations.
Checkpoint
11.2 Current author input configuration.
Conformance detail: For all content
1. Provide a centralized view of the current author-specified input
configuration.
Conformance detail: For user agent features
1. Allow the user to override any binding that is part of the user agent
default input configuration.
Conformance detail: For user agent features
1. Allow the user to override any binding in the user agent default
keyboard configuration with a binding to either a key plus modifier keys or
to a single key.
2. For each functionality in the set required by checkpoint 11.5, allow
the user to configure a single-key binding. A single-key binding is one where
a single key press performs the task, with zero modifier keys.
Conformance detail: For user agent features
1. Ensure that the user agent default input configuration includes
bindings for the following functionalities required by other checkpoints in
this document:
move content focus to the next enabled element in document order, and move
content focus to the previous enabled element in document order (checkpoints
9.3 and 9.7);
activate the link designated by the content focus (checkpoints 1.1 and
9.1);
search for text, search again for same text (checkpoint 9.8);
increase the scale of rendered text, and decrease the scale of rendered
text (checkpoint 4.1);
increase global volume, and decrease global volume (checkpoint 4.7);
and
stop, pause, resume, and navigate efficiently selected audio and
animations, including video and animated images (checkpoint 4.5).
2. If the user agent supports the following functionalities, the default
input configuration must also include bindings for them:
next history state (forward), and previous history state (back);
enter a URI for a new resource;
add a URI to favorites (i.e., bookmarked resources);
view favorites;
reload a resource;
interrupt a request to load or reload a resource;
for graphical viewports: navigate forward and backward through rendered
content by approximately the height of the viewport; and
for user agents that render content in lines of (at least) text: move the
point of regard to the next and previous line.
- EARL / CC/PP
- The use of RDF as a profiling mechanism allows for profiles to be
described in the CC/PP vocabulary and made avialable as conforming to
certain requirements, either expressed as EARL conformance to CC/PP
statements, or for IMS user profiles. Other profiles built on these
standardised bases can then be shared readily and interoperably.
Conformance detail: For user agent features
1. For graphical user agent user interfaces with tool bars, allow the user
to configure the position of user agent user interface controls on those tool
bars.
2. Offer a predefined set of controls that may be added to or removed from
tool bars.
3. Allow the user to restore the default tool bar configuration.
Guideline 12. Provide accessible user agent
documentation and help
Checkpoint
12.1 Provide accessible documentation.
Conformance detail: For user agent features
1. Ensure that at least one version of the user agent documentation
conforms to at least level Double-A of the Web Content Accessibility
Guidelines 1.0 [WCAG10].
Checkpoint
12.2 Provide documentation of accessibility features.
- Semantically described Tools
- providing machine-processable documentation of accessibility features
in the tool can help in generating the required information for other
checkpoint 12.5.
- Schema Annotation
- Schemas whose accessibility features are identified permit a user
agent to more clearly identify how it implements accessibility
features, combining this information with information about its own
accessibility to conform to this checkpoint.
Checkpoint
12.3 Provide documentation of default bindings.
Conformance detail: For user agent features
1. Provide documentation of the default user agent input configuration
(e.g., the default keyboard bindings).
Checkpoint
12.4 Provide documentation of changes between versions
- Describing Tools
- Providing machine-processable descriptions of features available in a
tool can automate some of this process.
Checkpoint
12.5 Provide dedicated accessibility section.
- Describing Tools
- Providing machine-processable descriptions of features available in a
tool can automate some of this process.
Guideline 1: Ensure that authors can associate multiple media objects as
alternatives
Checkpoint 1.1 Provide a mechanism to
explicitly associate alternatives for content or content fragments.
Checkpoint 1.2 Define flexible associations,
where a given kind of relationship can link to or from objects of varying
types without constraint.
Guideline 2. Create semantically-rich languages
Checkpoint 2.1 Ensure all semantics are
captured in markup in a repurposable form.
Checkpoint 2.2 Separate presentation
properties using stylesheet technology/styling mechanisms.
Checkpoint 2.3 Use the standard XML linking
and pointing mechanisms (XLink and XPointer).
Checkpoint
2.4 Define element types that allow classification and grouping (header,
section, list, etc).
Checkpoint 2.5 Provide for a full containment
model with chunks of reasonable size.
Checkpoint 2.6 Define element types that
identify important text content.
Checkpoint 2.7 Provide a mechanism for
identifying summary / abstract / title.
Checkpoint 2.8 Don't overload element and
attribute names.
Checkpoint
2.9 Reuse existing accessible modules, as originally specified /
intended.
- Schema Annotation
- Annotations for schema modules can describe their purpose, including
EARL documentation of their conformance to XAG, which would enable
searching for an appropriate module and judging the relative
accessibility. (Likewise, documentation of their implementations can be
useful).
Checkpoint 2.10 Allow association of
metadata with distinct elements and groups of elements.
- RDF data
- Providing a metadata element that allows for the direct inclusion of
RDF, or providing an explicit linkage to machine-readable data combined
with the ability to address distinct elements by URI, achieves
this.
Checkpoint 2.11 Specific checkpoint for
Final-form applications.
- Schema Annotation
- Annotating schemas to point out that they are intended only as a
final rendering format, and not as an authoring format, and pointing to
authoring formats that can be used to generate content for the format
may both be useful techniques for this checkpoint.
Guideline 3. Design an accessible user interface
Checkpoint 3.1 Provide default style sheets
for multiple output modalities.
Checkpoint 3.2 Define navigable structures
that allow discrete, sequential, structured, and search navigation
functionalities.
Checkpoint 3.3 Use CSS or XSLT to describe a
basic outline view
Checkpoint 3.4 Use a device-independent
interaction and events model / module.
Checkpoint 3.5 Allow for user control of
interaction timing - rate of change, external events triggering document
changes, etc.
Guideline 4 Document and export semantics
Checkpoint 4.1 Provide explicit human
readable definitions for markup semantics.
- Schema Annotation
- The use of an element within the schema language that is defined as a
natural language description can be processed by referring to RDF
descriptions of the schema language itself
- Annotea
- Annotea annotations can be used to provide human-readable information
about a part of an XML document, including one which describes the
elements and attributes which can be used in an XML language.
Checkpoint 4.2 Ensure that at least one
version of the XML application's documentation conforms to at least level
Double-A of the Web Content Accessibility Guidelines 1.0 [WCAG1].
Checkpoint 4.3 Provide a
machine-understandable means/mechanism to get from a document instance to the
schema.
- Versioning
- Where a document format does not differentiate versions, different
requirements may apply in different versions of a document's
definition. External descriptions can be use to identify which version
of a format a particular document instance uses.
Checkpoint 4.4 Use a schema language that can
support explicit human-readable documentation or annotation of semantics.
- Schema annotation
- Languages such as XML Schema allow explicit documentation of each
element.
- Annotea
- It is possible to use Annotea to annotate any XML langauge, including
one which describes a schema for a markup language, as well as any
element name which can be expressed as a URI with RDF.
Checkpoint 4.5 Provide semantic relationships
to other schema where appropriate and possible.
- RDF Vocabularies and OWL
- providing an RDF version of two schemata allows relations between
them to be declared in terms of properties defined by the RDF
Vocabulary specification (for subClasses, subTypes, and so on), OWL
(for further definition), or in specific RDF vocabularies developed
from the purpose.
Checkpoint 4.6 Document all features of the
XML application that benefit accessibility.
- Schema annotation
- An RDF vocabulary could be used to define types of accessibility
property. This can be used to automate the process of authoring tools
presenting accessibility functionalities, as required by ATAG
checkpoint 5.2
Checkpoint 4.7 Include accessibility
requirements in conformance requirements.
Checkpoint 4.8 Document techniques for WCAG,
ATAG, and UAAG with respect to the XML application.
- Schema Annotation
- In many cases existing techniques will work for new langauges.
Annotating the schema to point to existing techniques which are
applicable may considerably reduce the work required to conform to this
checkpoint.
Checkpoint 4.9 Do not assume that element or
attribute names provide any information about element semantics.
Checkpoint 4.10 Document navigable
structures. Describe how discrete, sequential, structured, and search
navigation mechanisms should work
- Site Mapping
- A vocabulary used for site mapping could be re-used to describe
navigation within documents as a general scheme.
Several general areas of work seem to offer promise in a numer of areas.
Additionally, there are some areas of work which don't cover a particular
checkpoint or guideline, but where the Semantic Web seems to offer an overall
improvement in the accessibility of a type of content:
- CC/PP
- CC/PP - the Composite Conformance / Preferences Profile is a W3C
specification describing, in RDF, a framework for negoatiating
different version of a resource according to the needs or preferences
of a user. Such needs or preferences may be determined by disability,
or equally by capabilities of the platform the user happens to have
available at a given moment.
- Describing Tools
- See Semantically described Services and
Tools
- EARL
- EARL - The Evaluation And Reporting Language is a W3C working draft
for an RDF language that can describe the results of conformance
evaluations. It was developed by the W3C's Evaluation and Repair Tools
Working Group, a part of the WAI Technical Activity.
- Mapping and geographical
information
- Current models for presenting geographical information on the Web
tend to revolve around images, with the notable exception of text-based
driving directions. The use of semantic Web technology for manipulating
geographic information could offer more accessible presentations of
such information on scales from the global to the location of things in
a room. Work in areas such as location-specific information on mobile
telephones, 'webtiles', and wayfinding services, show some of the
interactions between information that is or could be in the Semantic
Web and people's everday lives in the physical world.
- Multimedia annotations
- One of the large areas of accessibility concern is multimedia,
because people with disabilities may not be able to use all the media
concerned, or may not be able to work simultaneously with the multiple
media. There are many techniques which can be used to provide
supplementary information about media objects, that can be used in
authoring support, or in user agents.
- Schema Annotation
- Annotating schema definitions directly can be used by authoring tools
in many ways to support accessible use of an XML vocabulary. It can
also provide clues for evaluation or presentation in user agents, with
the use of machine-processable annotations.
- Semantically described services
and tools
- Providing machine-processable descriptions of tool functionalities
(including Web services) can allow users to find or incorporate into
the framework of their work environment an appropriate alternative to a
particular functionality without having to change their toolset
completely. For users who reqiure assistive technologies it can also
simplify the process of integration into their work style, or even
managing compatibility.
- Text annotation
- The techniques available for multimedia annotation can also be
applied to addressable text on the Web, noting simpler, more
interactive, or otherwise different presentations of it.
- User profiles
- There are a number of possible approaches to defining a user's
preferences and requirements which can be used to determine whether a
(possibly) more suitable version of content can be offered than might
otherwise be the case. These techniaques can also be applied to
configuration requirements, a major part of the User Agent
Accessibility Guidelines, and which are also required by the Authoring
Tool Accessbility Guidelines.
Some of the appraoches described above have existing implentation as
either a product or a proof-of-concept. Others are in development at the time
of writing. Although any survey of implementations is unlikely to be
exhaustive, the following are some that may be of interest. None of these
implmentations are endorsed as being a usful, accurate, or fit implementation
of any particular approach, and this list is known to be arbitrary and
primarily focused on European-developed Open Source technology. However
information about semantic web tools for accessibility can be sent to
public-esw or wai-er-ig with a request that they be incorporated into this
list during the life of this document.
The MUTAT evaluation tool [MUTAT] was adapted to use
Annotea as a storage and retrieval system, working with the experimental EARL
server provided by W3C. The Axform tool suite [AXFORM]
has been developed as a replacement, using Xforms technology to replace
server scripting for greater portability.
Accessibility testing tools including Access Valet,
AccVerifyTM, Axform, WAINu, produce reports in EARL of the
accessibility of Web Content. A list of many accessibility testing tools [ERTools] is maintained by WAI.
RDFPic [RDFPic] demonstrates image annotations
included in an image file. (Further tools for manipulating this information
have been produced by Norm Walsh [JPEGRDF]).
Jim Ley's image annotation tools [JImAnno]
demonstrate the use of annotations stored seperately from the image file.
See CC/PP implementation
information maintained by W3C's Device Independence Activity.
The next stage in this workpackage is to work with WAI to determine which
of the suggestions in this document are considered valuable techniques,
providing further details or implementation examples as necessary, and
incorporating them into the relevant techniques Notes where appropriate.
Some of this work has now been done, including presenting some RDF
techniques to the Web Content Accessiblilty Guidelines working group meeting
in Venice, July 2003, and presenting (by email) some tools developed for EARL
as part of this project. Further work with WAI, the Dublin Core Metadata
Initiative's Accessibility Interest Group, and the EuroAccessibility
Consortium in particular, is anticipated.
- [ANNOCOL]
- The Annotea
protocol is documented at
http://www.w3.org/2001/Annotea/User/Protocol
- [ANNOTEA-R]
- The Schema for threaded
annotations, developed to allow for threaded responses, is
available at http://www.w3.org/2001/03/thread
- [ANNOTOOLS]
- A small library
of tools developed for use with the Annotea protocol, and as
example code for people wanting to develop their own tools. These tools
are described at
http://www.w3.org/2001/sw/Europe/200209/annodemo/readme.html
- [ATAG1]
- "Authoring Tool Accessibility
Guidelines 1.0" ed. Jacobs, McCathieNevile, Richards, Treviranus is
a W3C Recommendation published on 2 February 2000. It is available at
http://www.w3.org/TR/ATAG10
- [ATAG2]
- "Authoring Tool Accessibility
Guidelines 2.0" ed. McCathieNevile, May, Richards, Treviranus is a
W3C Working Draft. It is available at http://www.w3.org/TR/ATAG20
- [ANNOT-IMPLE]
- A list of known Annotea
Implementations is maintained by W3C's Annotea project at
http://www.w3.org/2001/Annotea/#Comp
- [AXFORM]
- Some Xforms-based tools for creating
EARL evaluations, designed as a replacement for the MUTAT tool.
Available at http://www.w3.org/2001/sw/Europe/200305/axforms/
- [EARL]
- EARL (The Evaluation and
Reporting Language) is a specification in development by the W3C's
Evaluation and Repair Tools group. It is an RDF vocabulary for
expressing conformance to arbitrary requirements. The Latest published
draft is available at http://www.w3.org/TR/EARL10
- [ERTools]
- WAI maintains a list of tools for accessibility
evaluation and repair, at
http://www.w3.org/WAI/ER/existingtools
- [JImAnno]
- Some tools for annotating images through SVG. Available from produced
by Jim Ley.
- [MUTAT]
- The Open Source MUTAT
tool is designed to provide an interview-style interface for
producing conformance reports in the EARL [EARL]
format. It has an extension which allows the reports to be posted as
annotations to an annotea server. An online version of the Tool is
available at http://www.w3.org/QA/Tools/MUTAT/
- [JPEGRDF]
- Norm Walsh's tools for
working with RDF in JPEG files. Available from
http://nwalsh.com/java/jpegrdf/
- [RDFPic]
- A tool for adding RDF to a
JPEG image file developed at W3C. Available from
http://jigsaw.w3.org/rdfpic
- [UAAG]
- The "User Agent Accessibility
Guidelines 1.0", ed. Gunderson, Hansen, Jacobs, is a W3C
Recommendation published on 17 December 2002, available at
http://www.w3.org/TR/UAAG10
- [WCAG1]
- The "Web Content Accessibility
Guidelines 1.0", ed. Chisholm, Jacobs, Vanderheiden is a W3C
Recommendation published on 5 May 1999, available at
http://www.w3.org/TR/WCAG10
- [WCAG2]
- The "Web Content Accessibility
Guidelines 2.0", ed. Caldwell, Chisholm, White, Vanderheiden is a
W3C Working Draft. The version used in this report was published on 22
August 2002, and the latest version is available at
http://www.w3.org/TR/WCAG20
- [WWW-ANNOTATION]
- The www-annotation@w3.org mailing list is a public discussion forum
for annotation systems, including Annotea. Its
archives (including instructions for subscribing) are available at
http://lists.w3.org/Archives/Public/www-annotation/
- [XAG]
- "XML Accessibility Guidelines"
ed. Dardailler, McCathieNevile, Palmer is a W3C Working Draft. The The
version used in this report was published on 3 October 2002, and the
latest version is available at http://www.w3.org/TR/xag
- [LICENSE]
- The W3C
Software Copyright license is a BSD-style license allowing the free
use of software in open-source or proprietary products with appropriate
acknowledgement. The full license is available at
http://www.w3.org/Consortium/Legal/copyright-software