might be spoken "start Spanish _Esta pagina en espanol_ end Spanish".
Refer also to information on matching attributes and attribute values
useful for language matching in CSS 2 ([CSS2], section 5.8.1).
If users don't want to see or hear blocks of content in another
language, allow the user to suggest hiding that content (e.g.,
with style sheets).
+ Implement content negotiation so that users may specify
language preferences. Or allow the user to choose a resource
when several are available in different languages.
+ Use an appropriate glyph set when rendering visually.
+ Use an appropriate voice set when rendering as speech.
+ Render characters with the appropriate directionality. Refer
to the "dir" attribute and the BDO element in HTML 4.0
([HTML40], sections 8.2 and 8.2.4 respectively). Refer also
to the Unicode standard [UNICODE].
+ A user agent may not be able to render all characters in a
document meaningfully, for instance, because the user agent
lacks a suitable font, a character has a value that may not
be expressed in the user agent's internal character encoding,
etc. In this case, section 5.4 of HTML 4.0 [HTML40]
recommends the following for undisplayable characters:
1. Adopt a clearly visible (or audible), but unobtrusive
mechanism to alert the user of missing resources.
2. If missing characters are presented using their numeric
representation, use the hexadecimal (not decimal) form
since this is the form used in character set standards.
+ Refer to "Character Model for the World Wide Web" [CHARMOD],
which defines various aspects of a character model for the
World Wide Web. It contains basic definitions and models,
specifications to be used by other specifications or directly
by implementations, and explanatory material. In particular,
early uniform normalization, string identity matching, string
indexing, and conventions for URIs are addressed.
+ For information on language codes, refer to [ISO639].
__________________________________________________________
Guideline 3. Allow the user to turn off rendering or behavior that may reduce
accessibility
In addition to the techniques below, refer also to the section on user
control of style.
Checkpoints for content accessibility:
3.1 Allow the user to turn on and off rendering of background images.
[Priority 1]
Techniques:
+ Allow the user to turn off embedded or background images
through the user agent user interface. Note that any
equivalent alternatives for those images must still be
available.
+ In CSS background images may be turned on/off with the
'background' and 'background-image' properties ([CSS2],
section 14.2.1).
__________________________________________________________
3.2 Allow the user to turn on and off rendering of background audio.
[Priority 1]
Techniques:
+ Allow the user to turn off background audio through the user
agent user interface.
+ Authors sometimes specify background sounds with the
"bgsound" attribute. Note. This attribute is not part of HTML
4.0 [HTML40].
+ In CSS 2, background sounds may be turned on/off with the
'play-during' property ([CSS2], section 19.6).
__________________________________________________________
3.3 Allow the user to turn on and off rendering of video. [Priority 1]
Techniques:
+ Allow the user to turn off video through the user agent user
interface. Render a still image in its place.
+ Support the 'display' property in CSS.
__________________________________________________________
3.4 Allow the user to turn on and off rendering of audio. [Priority 1]
Techniques:
+ Allow the user to turn off audio through the user agent user
interface.
+ Support the CSS 2 'display', 'play-during', and 'speak'
properties in ([CSS2], sections 9.2.5, 19.6, and 19.5,
respectively).
__________________________________________________________
3.5 Allow the user to turn on and off animated or blinking text.
[Priority 1]
Techniques:
+ Allow the user to turn off animated or blinking text through
the user agent user interface (e.g., by hitting the ESCAPE
key to stop animations). Render static text in place of
blinking text.
+ The BLINK element. Note. The BLINK element is not defined by
a W3C specification.
+ The MARQUEE element. Note. The MARQUEE element is not defined
by a W3C specification.
+ The CSS 'blink' value of the 'text-decoration' property.
__________________________________________________________
3.6 Allow the user to turn on and off animations and blinking images.
[Priority 1]
Techniques:
+ Allow the user to turn off animated or blinking text through
the user agent user interface (e.g., by hitting the ESCAPE
key to stop animations). Render a still image in its place.
__________________________________________________________
3.7 Allow the user to turn on and off support for scripts and applets.
[Priority 1]
Note. This is particularly important for scripts that cause the
screen to flicker, since people with photosensitive epilepsy
can have seizures triggered by flickering or flashing,
particularly in the 4 to 59 flashes per second (Hertz) range.
Techniques:
Peak sensitivity to flickering or flashing occurs at 20 Hertz.
Refer to the section on script techniques
__________________________________________________________
3.8 For automatic content changes specified by the author (e.g.,
content refresh and page forwards), allow the user to slow the
rate of change. [Priority 2]
For example, alert the users to pages that refresh
automatically and allow them to specify a refresh rate. For
example, allow the user to slow content refresh to once per 10
minutes. Or, allow the user to stop automatic refresh, but
indicate that content needs refreshing and allow the user to
refresh the content by activating a button or link.
Techniques:
Content refresh according to an author-specified time interval
can be achieved with the following markup in HTML:
The user agent should allow the user to slow (e.g., by
configuring the rate of change in seconds) or disable this type
of content refresh.
Although no HTML specification defines this behavior formally,
some user agents support the use of the META element to refresh
the current page after a specified number of seconds, with the
option of replacing it by a different URI. Instead of this
markup, authors should use server-side redirects (with HTTP).
User agents can provide a link to other content rather than
changing the content automatically.
User agents may also prompt the user and ask whether to
continue with forwards.
__________________________________________________________
3.9 Allow the user to turn on and off rendering of images.
[Priority 3]
Techniques:
+ Provide a simple command that allows users to toggle on and
off the rendering of images on a page. This will be useful to
users who wish to switch between viewing the images and the
corresponding text equivalents.
+ Refer to techniques for checkpoint 3.1.
__________________________________________________________
Guideline 4. Ensure user control of styles
In addition to the techniques below, refer also to the section on user
control of style.
Checkpoints for fonts and colors:
4.1 Allow the user to configure the size of text. [Priority 1]
For example, allow the user to specify a font family and style
directly through the user agent user interface or in a user
style sheet. A zoom or magnification feature would also satisfy
this checkpoint.
Techniques:
+ Inherit text size information from user's settings for the
operating system.
+ Use system features for magnification/shrinking.
+ Implement the CSS 'font-size' property.
+ Allow the user to configure the user agent to ignore
author-specified font size.
+ Allow the user to scale text while retaining relative sizes
among text of different sizes.
__________________________________________________________
4.2 Allow the user to configure font family. [Priority 1]
Techniques:
+ Implement the CSS 'font-family' property.
+ Allow the user to override the author's specified fonts.
+ Inherit font information from user's settings for the
operating system.
__________________________________________________________
4.3 Allow the user to configure foreground color. [Priority 1]
Techniques:
+ Implement the CSS 'color' and 'border-color' properties.
+ Allow the user to specify minimal contrast between foreground
and background colors, adjusting colors dynamically to meet
those requirements.
+ Allow the user to impose a specific foreground color,
ignoring author-supplied colors.
+ Inherit foreground color information from user's settings for
the operating system.
__________________________________________________________
4.4 Allow the user to configure background color. [Priority 1]
Techniques:
+ Implement the CSS 'background-color' property and other
background properties.
+ Allow the user to impose a specific background color,
ignoring author-supplied colors.
+ Inherit background color information from user's settings for
the operating system.
__________________________________________________________
Checkpoints for multimedia:
4.5 Allow the user to slow the presentation rate of audio, video, and
animations. [Priority 1]
Techniques:
Typically, video, animation, and audio are intended to provide
information to the user at a rate that allows comfortable
processing of the information for the typical user. However,
for some users, this rate may be too fast to allow the
information to be processed, which makes it inaccessible to the
user. Such users may include individuals with specific learning
disabilities, cognitive deficits, or those with normal
cognition but newly acquired sensory limitations (such as the
person who is newly blind, learning to use a screen reader).
The same difficulty is common among individuals who have
beginning familiarity with a language.
For these individuals, the ability to slow the rate of
presentation of information to match the individual's
processing speed can make that information accessible. Since
simply slowing the rate of transmission of an audio track will
introduce pitch distortion that may likewise render the
information inaccessible, a user agent providing rate
configuration should also provide pitch compensation to
compensate for different playback speeds.
Note. User agents may not be able to slow the playback rate for
some formats. There are techniques to slow audio without
leading to distortion.
__________________________________________________________
4.6 Allow the user to start, stop, pause, advance, and rewind audio,
video, and animations. [Priority 1]
Techniques:
+ Allow the user to advance or rewind the presentation in small
increments. This is particularly valuable to users with
physical disabilities who may not have fine control over
advance and rewind functionalities. Allow users to configure
the size of the increments.
+ Let the advance/rewind distances be proportional to the time
you activate the corresponding button.
+ Home Page Reader lets you insert slowdowns in the middle of a
presentation to let you know where you are.
+ Implement an acceleration feature: the longer you hold, the
faster the advance and rewind.
+ There are well-known techniques for changing audio speed
without introducing distortion.
__________________________________________________________
4.7 Allow the user to configure the audio volume. [Priority 2]
4.8 Allow the user to configure the position of captions on graphical
displays. [Priority 1]
Checkpoints for synthesized speech:
4.9 Allow the user to configure synthesized speech playback rate.
[Priority 1]
Techniques:
+ In CSS2, use the 'speech-rate' property.
__________________________________________________________
4.10 Allow the user to configure synthesized speech volume.
[Priority 1]
4.11 Allow the user to configure synthesized speech pitch, gender, and
other articulation characteristics. [Priority 2]
Checkpoints for user interface accessibility:
4.12 Allow the user to select from available author and user style
sheets or to ignore them. [Priority 1]
Note. By definition the browser's default style sheet is always
present, but may be overridden by author or user styles.
Techniques:
+ Make available "class" and "id" information so that users can
override styles.
+ Allow the user to define custom styles for "class" and "id"
attributes specified in the document.
__________________________________________________________
4.13 Allow the user to configure how the selection is highlighted
(e.g., foreground and background color). [Priority 1]
Techniques:
+ For instance, in X Windows, the following resources controls
the selection colors in Netscape Navigator:
"*selectForeground" and "*selectBackground".
+ Implement the CSS 2 "HighLightText and "Highlight" predefined
color values ([CSS2], section 18.2).
+ Inherit content focus information from user's settings for
the operating system.
__________________________________________________________
4.14 Allow the user to configure how the content focus is highlighted
(e.g., foreground and background color). [Priority 1]
4.15 Allow the user to configure how the focus changes. [Priority 2]
For instance, allow the user to require that user interface
focus not move automatically to spawned viewports
Techniques:
Allow the user to configure how current focus changes when a
new viewport is spawned. For instance:
+ Never change the current focus, but notify the user that a
new window has appeared. Allow quick navigation to that
window so that the user may shift focus there once their
current activity has ended.
+ Always change the current focus and use a discrete alert
(e.g., a flash or beep) to indicate that the current focus
has changed.
Note that if a new viewport or prompt appears but focus does
not move to it, assistive technologies should still be notified
so that they may (discretely) inform the user, allow querying,
etc.
__________________________________________________________
4.16 Allow the user to configure user agent initiated spawned
viewports, prompts, and other windows. [Priority 2]
For instance, allow the user to cancel viewport creation. Refer
also to checkpoint 5.4.
Techniques:
User agents may:
+ In HTML [HTML40], allow the user to control the process of
opening a document in a new "target" frame or a viewport
created by author-supplied scripts.
+ In SMIL [SMIL], allow the user to control viewports created
with the "new" value of the "show" attribute.
+ Allow users to turn off support for spawned viewports
entirely
+ Prompt them before spawning a viewport. For instance, for
user agents that support CSS2 [CSS2], the following rule will
generate a message to the user at the beginning of link text
for links that are meant to open new windows when followed:
A[target=_new]:before{content:"Open new window"}
+ Users may also want to configure the size or position of the
viewport and to be able to close the viewport (e.g., with the
"back" functionality).
For example, user agents may recognize the HTML construct
target="_blank" and spawn the window according to the user's
preference.
__________________________________________________________
Guideline 5. Observe system conventions and standard interfaces
Checkpoints for content accessibility:
5.1 Provide programmatic read and write access to content by
conforming to W3C Document Object Model (DOM) specifications
and exporting interfaces defined by those specifications.
[Priority 1]
For example, refer to DOM Levels 1 and 2 ([DOM1], [DOM2]). User
agents should export these interfaces using available operating
system conventions.
Techniques:
A Document Object Model (DOM) is an interface to a standardized
tree structure representation of a document. This interface
allows authors to access and modify the document with
client-side scripting language (e.g., JavaScript) in a
consistent manner across scripting languages. As a standard
interface, a DOM makes it easier not just for authors but for
assistive technology developers to extract information and
render it in ways most suited to the needs of particular users.
Information of particular importance to accessibility that must
be available through the DOM includes:
+ Content, including equivalent alternatives.
+ Style sheet information (for user control of styles).
+ Script and event handlers (for device-independent control of
behavior).
+ The document structure (for navigation, creation of
alternative views).
User agents should implement W3C DOM Recommendations, including
DOM Level 1 [DOM1] and DOM Level 2 [DOM2]]. The W3C
Recommendation for DOM Level 1 ([DOM1]) provides access to HTML
and XML document information. The DOM Level 2 ([DOM2]) is made
of a set of core interfaces to create and manipulate the
structure and contents of a document and a set of optional
modules. These modules contain specialized interfaces dedicated
to XML, HTML, an abstract view, generic stylesheets, Cascading
Style Sheets, Events, traversing the document structure, and a
Range object.
It is important to note that DOM is designed to be used on a
server as well as a client and therefore a lot of user
interface-specific information such as screen coordinate
information is not relevant and not addressed by the DOM
specification.
Assistive technologies also require information about browser
highlight mechanisms (e.g., the selection and focus) that may
not be available through the W3C DOM.
The DOM Level 1 specification states that "DOM applications may
provide additional interfaces and objects not found in this
specification and still be considered DOM compliant."
Note. The WAI Protocols and Formats Working Group is focusing
its efforts on the DOM as the conduit from which to extract
accessibility information and enhance the accessibility of a
rendered document through a user agent.
__________________________________________________________
Checkpoints for user interface accessibility:
5.2 Provide programmatic read and write access to user agent user
interface controls using standard APIs (e.g.,
platform-independent APIs such as the W3C DOM, standard APIs
for the operating system, and conventions for programming
languages, plug-ins, virtual machine environments, etc.)
[Priority 1]
For example, ensure that assistive technologies have access to
information about the current input configuration so that they
can trigger functionalities through keyboard events, mouse
events, etc.
Techniques:
The operating system APIs that support accessibility are
designed to provide a bridge between the standard user
interface supported by the operating system and alternative
user interfaces developed by third-party assistive technology
vendors to provide access to persons with disabilities.
Applications supporting these APIs are therefore generally more
compatible with third-party assistive technology.
The User Agent Accessibility Guidelines Working Group strongly
recommends using and supporting APIs that improve accessibility
and compatibility with third-party assistive technology.
Third-party assistive technology can use the accessibility
information provided by the APIs to provide an alternative user
interface for various disabilities.
The following is an informative list of currently public APIs
that promote accessibility:
+ Microsoft Active Accessibility ([MSAA]) in Windows 95/98/NT
versions.
+ Sun Microsystems Java Accessibility API ([JAVAAPI]) in Java
Code. If the user agent supports Java applets and provides a
Java Virtual Machine to run them, the user agent should
support the proper loading and operation of a Java native
assistive technology. This assistive technology can provide
access to the applet as defined by Java accessibility
standards.
Thus, developers should use the platform's standard user
interface components whenever possible and ensure that custom
components provide equivalent accessibility information as
standard user interface components in the same programmatic
way. For other user interface components not based on a
platform's standard toolkit, provide information and events
equivalent to that found in currently available accessibility
APIs (e.g., JAAPI and MSAA).
Many operating systems have built-in accessibility features for
improving the usability of the standard operating system by
persons with disabilities. When designing software that runs
above an underlying operating system, developers should ensure
that the application:
1. Makes use of operating system level features. See the
appendix of accessibility features for some common operating
systems.
2. Inherits operating system settings related to accessibility.
Pertinent settings include font and color information and
other information described in this document.
Write output to and take input from standard system APIs rather
than directly from hardware controls where possible. This will
enable the I/O to be redirected from or to assistive technology
devices - for example, screen readers and Braille displays
often redirect output (or copy it) to a serial port, while many
devices provide character input, or mimic mouse functionality.
The use of generic APIs makes this feasible in a way that
allows for interoperability of the assistive technology with a
range of applications.
User agents should use standard rather than custom controls
when designing user agents. Third-party assistive technology
developers are more likely able to access standard controls
than custom controls. If you must use custom controls, review
them for accessibility and compatibility with third-party
assistive technology.
For information about rapid access to Microsoft Internet
Explorer's DOM through COM, refer to [BHO].
__________________________________________________________
5.3 Implement selection, content focus, and user interface focus
mechanisms. [Priority 1]
Refer also to checkpoint 7.1 and checkpoint 5.2. Note. This
checkpoint is an important special case of checkpoint 5.2.
5.4 Provide programmatic notification of changes to content and user
interface controls (including selection, content focus, and
user interface focus). [Priority 1]
Techniques:
Assistive technologies may not "want" notification of all
changes. User agents providing notification may allow
configuration of preferred notifications. If user agents
providing notification do not allow configuration, assistive
technologies may filter out unwanted notifications.
__________________________________________________________
Refer also to checkpoint 5.2.
5.5 Ensure that programmatic exchanges proceed in a timely manner.
[Priority 2]
Techniques:
+ @@This needs work and probably should be in the guidelines@@.
The exchange of information between user agents must keep
pace with changes in the content. It may be necessary to
allow the user to configure the user agent to pause before
changes to content or the user interface so that an assistive
technology has time to react.
+ Please refer to the appendix that explains how to load
assistive technologies for DOM access.
__________________________________________________________
5.6 Follow operating system conventions and accessibility settings. In
particular, follow conventions for user interface design,
default keyboard configuration, product installation, and
documentation. [Priority 2]
Refer also to checkpoint 10.2.
Techniques:
Develop the user interface with standard components per the
target platform(s). Most major operating system platforms
provide a series of design and usability guidelines; these
should be followed when possible (see platforms below). These
checklists, style guides, and human interface guidelines
provide very valuable information for developing applications
(e.g., UAs) for any platform/operating system/GUI.
For instance, software should use the standard interface for
keyboard events rather than working around it.
Evaluate your standard interface components on the target
platform against any built in operating system accessibility
functions (see Appendix 8) and be sure your UA operates
properly with all these functions.
For example, take caution with the following:
+ Microsoft Windows supports an accessibility function called
"High Contrast". Standard window classes and controls
automatically support this setting. However, applications
created with custom classes or controls must understand how
to work with the "GetSysColor" API to ensure compatibility
with High Contrast.
+ Apple Macintosh supports an accessibility function called
"Sticky Keys". Sticky Keys operates with keys the operating
system recognizes as modifier keys, and therefore a custom UA
control should not attempt to define a new modifier key.
+ Respect default input configurations for the operating
system. For example, the default configuration should not
include "Alt-F4" or "Control-Alt-Delete" on operating systems
where that combination has special meaning to the operating
system.
Some guidelines for specific platforms:
+ "Macintosh Human Interface Guidelines" [APPLE-HI] Apple
Computer Inc.
+ "IBM Guidelines for Writing Accessible Applications Using
100% Pure Java" [JAVA-ACCESS].
+ "An ICE Rendezvous Mechanism for X Window System Clients"
[ICE-RAP].
+ "Information for Developers About Microsoft Active
Accessibility" [MSAA].
+ "The Inter-Client communication conventions manual" [ICCCM].
+ "Lotus Notes accessibility guidelines" [NOTES-ACCESS].
+ "Java accessibility guidelines and checklist"
[JAVA-CHECKLIST].
+ "The Java Tutorial. Trail: Creating a GUI with JFC/Swing"
[JAVA-TUT].
+ "The Microsoft Windows Guidelines for Accessible Software
Design" [MS-SOFTWARE].
General guidelines for producing accessible software:
+ "Accessibility for applications designers" [MS-ENABLE].
+ "Application Software Design Guidelines" [TRACE-REF].
+ "Designing for Accessibility" [SUN-DESIGN].
+ "EITAAC Desktop Software standards" [EITAAC].
+ "Requirements for Accessible Software Design" [ED-DEPT].
+ "Software Accessibility" [IBM-ACCESS].
+ Towards Accessible Human-Computer Interaction" [SUN-HCI].
+ "What is Accessible Software" [WHAT-IS].
+ Accessibility guidelines for Unix and X Window applications
[XGUIDELINES].
Follow System Conventions for loading Assistive Technologies:
User agents should follow operating system or application
environment (e.g., Java) conventions for loading assistive
technologies. In the case of Java applets, the browser's Java
Virtual Machine should follow the Sun convention for loading an
assistive technology. Writing an application that follows the
Java system conventions for accessible software does not allow
the applet to be accessible if an assistive technology designed
for that environment cannot be run to make the applet
accessible. Refer to the appendix on loading assistive
technologies for DOM access for information about how an
assistive technology developer can load its software into a
Java Virtual Machine.
__________________________________________________________
Guideline 6. Implement accessible specifications
Checkpoints for content accessibility:
6.1 Implement the accessibility features of supported specifications
(markup languages, style sheet languages, metadata languages,
graphics formats, etc.). [Priority 1]
Note. The Techniques Document [UA-TECHNIQUES] addresses the
accessibility features of W3C specifications.
Techniques:
+ Features that are known to promote accessibility should be
made obvious to users and easy to find.
+ The accessibility features of Cascading Style Sheets ([CSS1],
[CSS2]) are described in "Accessibility Features of CSS"
[CSS-ACCESS]. Note that CSS 2 includes properties for
configuring synthesized speech styles.
+ The accessibility features of SMIL 1.0 [SMIL] are described
in "Accessibility Features of SMIL" [SMIL-ACCESS].
+ The following is a list of accessibility features of HTML 4.0
[HTML40] in addition to those described in techniques for
checkpoint 2.1:
o The CAPTION element (section 11.2.2) for rich table
captions.
o Table elements (THEAD, TBODY, TFOOT (section 11.2.3),
COLGROUP, and COL (section 11.2.4) that group table
rows and columns into meaningful sections.
o Attributes ( "scope", "headers", and "axis", section
11.2.6) that non-visual browsers may use to render a
table in a linear fashion, based on the semantically
significant labels.
o The "tabindex" attribute (section 17.11.1) for assigning
the order of keyboard navigation within a document.
o The "accesskey" attribute (section 17.11.2) for
assigning keyboard commands to active components such as
links and form controls.
__________________________________________________________
6.2 Conform to W3C specifications when they are appropriate for a
task. [Priority 2]
For instance, for markup, implement HTML 4.0 [HTML40] or XML
1.0 [XML]. For style sheets, implement CSS ([CSS1], [CSS2]).
For mathematics, implement MathML [MATHML]. For synchronized
multimedia, implement SMIL 1.0 [SMIL]. For access to the
structure of HTML or XML documents, implement the DOM ([DOM1],
[DOM2]). Refer also to checkpoint 5.1.
Note. For reasons of backward compatibility, user agents should
continue to support deprecated features of specifications. The
current guidelines refer to some deprecated language features
that do not necessarily promote accessibility but are widely
deployed. Information about deprecated language features is
generally part of the language's specification.
Guideline 7. Provide navigation mechanisms
Checkpoints for user interface accessibility:
7.1 Allow the user to navigate viewports (including frames).
[Priority 1]
Note. For example, when all frames of a frameset are displayed
side-by-side, allow the user to navigate among them with the
keyboard. Or, when frames are accessed or viewed one at a time
(e.g., by a text browser or speech synthesizer), provide a list
of links to other frames. Navigating into a viewport makes it
the current viewport.
Techniques:
+ Some operating systems provide a means to navigate among all
open windows using multiple input devices (e.g., keyboard and
mouse). This technique would suffice for switching among user
agent viewports that are separate windows. However, user
agents may also provide a mechanism to shift the user
interface focus among user agent windows, independent of the
standard operating system mechanism.
+ Consult the section on frame techniques.
__________________________________________________________
7.2 For user agents that offer a browsing history mechanism, when the
user returns to a previous viewport, restore the point of
regard in the viewport. [Priority 1]
For example, when users navigate "back" and "forth" among
viewports, they should find the viewport position where they
last left it.
7.3 Allow the user to navigate all active elements. [Priority 1]
Navigation may include non-active elements in addition to
active elements. Note. This checkpoint is an important special
case of checkpoint 7.6.
Techniques:
2.7.1 Sequential navigation techniques
Allow the user to sequential navigate all active elements using
a single keystroke. User agents might also provide other
sequential navigation mechanisms for particular element types
or semantic unit. For example "Find the next table" or "Find
the previous form".
It is important that application developers maintain a logical
element navigation order. For instance, users may use the
keyboard to navigate among elements or element groups and using
the arrow keys within a group of elements. One example of a
group of elements is a set of radio buttons. Users should be
able to navigate to the group of buttons, then be able to
select each button in the group. Similarly, allow users to
navigate from table to table, but also among the cells within a
given table (up, down, left, right, etc.)
+ How to indicate that something is in navigation order in
Java: A component is inclusive in the sequential navigation
order when added to a panel and its isFocusTraversable()
method returns true. A component can be removed from the
navigation order by simply extending the component,
overloading this method, and returning false.
+ Give the users the option of navigating to and activating a
link, or just moving the content focus to the link. When the
user returns to the page after following the link, restore
content focus to that link.
+ Many user agents today allow users to navigate sequentially
by repeating a key combination -- for example, using the
"tab" key for forward navigation and "shift-tab" for reverse
navigation. Because the "tab" key is typically on one side of
the keyboard while arrow keys are located on the other, users
should be allowed to configure the user agent so that
sequential navigation is possible with keys that are
physically closer to the arrow keys. Refer also to checkpoint
10.4.
+ The default sequential navigation order should respect the
conventions of the natural language of the document. Thus,
for most left-to-right languages, the usual navigation order
is top-to-bottom and left-to-right. Thus, for right-to-left
languages, the order would be top-to-bottom and
right-to-left.
The following view from Jaws for Windows allows users to
navigate links in a document and to select whether to navigate
visited, unvisited, or both types of links:
Jaws for Window Links List view
2.7.2 Direct navigation techniques
Excessive use of sequential navigation can reduce the usability
of software for both disabled and non-disabled users. Direct
navigation (e.g., through keyboard shortcuts) should also be
possible. Providing direct navigation involves:
+ Assigning each active element a unique identifier (or use the
identifier provided by the author, e.g., "accesskey" in
HTML). For example number each active element in a document.
+ Documenting how the user may access elements.
+ Allowing direct navigation by element content (e.g., the
first letter of element content).
+ Allowing direct navigation to a table cell by its row/column
position.
+ Allow searching (e.g., based on form control text, associated
labels, or form control names).
__________________________________________________________
7.4 Allow the user to choose to navigate only active elements.
[Priority 2]
Techniques:
Refer to techniques for checkpoint 7.3.
__________________________________________________________
7.5 Allow the user to search for rendered text content, including
rendered text equivalents. [Priority 2]
Note. Use operating system conventions for marking the result
of a search (e.g., selection or content focus).
Techniques:
+ Allow users to search for element content and attribute
values (human-readable ones).
+ Allow forward and backward searching from the point of
regard, beginning of document, or end of document.
+ Allow users to search the document source view.
+ For forms, allow users to find required controls. Allow users
to search on labels as well as content of some controls.
+ Allow the user to search among just text equivalents of other
content.
+ For multimedia presentations:
o Allow users to search and examine time-dependent media
elements and links in a time-independent manner. For
example, present a static list of time-dependent links.
o Allow users to find all media elements active at a
particular time in the presentation.
o Allow users to view a list of all media elements or
links of the presentations sorted by start or end time
or alphabetically.
o For frames, allow users to search for content in all
frames (without having to be in a particular frame).
__________________________________________________________
7.6 Allow the user to navigate according to structure. [Priority 2]
For example, allow the user to navigate familiar elements of a
document: paragraphs, tables and table cells, headers, lists,
etc. Note. Use operating system conventions to indicate
navigation progress (e.g., selection or content focus).
Techniques:
+ DOM is minimal (tree navigation)
+ Best navigation will involve a mix of source tree information
and rendered information.
+ May use commonly understood document models rather than
strict Document Type Definition (DTD) navigation. E.g.,
properly nesting headers in HTML. Headers should be used only
to convey hierarchy, not for graphical side-effects.
+ Allow the user limit navigation to the cells of a table
(notably left and right within a row and up and down within a
column). Navigation techniques include keyboard navigation
from cell to cell (e.g., using the arrow keys) and page
up/down scrolling. Refer to the section on table navigation.
+ Goal of simplifying the structure view as much as possible.
+ Allow the user to configure level of detail/ view of
structure.
+ Depth first as well as breadth first possible. Allow
next/previous sibling, up to parent, and end of element.
+ Navigation of synchronized multimedia: allow users to stop,
pause, fast forward, advance to the next clip, etc.
+ Allow the user to navigate characters, words, sentences,
paragraphs, screenfuls, and other language-dependent pieces
of text content. This may be particularly useful with a
speech-based user interface. Precise and flexible navigation
of this kind with a system cursor is often useful when
browsing with accessibility aids. Evidence of this point is
that the leading Windows screen readers have super-imposed
such navigation on a popular web browser that does not
natively support it (e.g., Winvision, Window-Eyes, and JAWS
with Internet Explorer).
Skipping navigation bars:
Author-supplied navigation mechanisms such as navigation bars
at the top of each page may force users with screen readers or
some physical disabilities to wade through numerous links on
each page of a site. User agents may facilitate browsing for
these users by allowing them to skip recognized navigation bars
(e.g., through a configuration option). Some techniques for
doing so include:
1. Provide a functionality to jump to the first non-link
content.
2. In HTML, the MAP element may be used to mark up a navigation
bar (even when there is no associated image). Thus, users
might ask that MAP elements not be rendered in order to hide
links inside the MAP element. Note. Starting in HTML 4.0, the
MAP element allows block content, not just AREA elements.
__________________________________________________________
7.7 Allow the user to configure structured navigation. [Priority 3]
For example, allow the user to navigate only paragraphs, or
only headers and paragraphs, etc.
Techniques:
+ Allow the user to navigate by element type.
+ Allow the user to navigate HTML elements that share the same
"class" attribute.
+ Allow the user to expand or shrink portions of the structured
view (configure detail level) for faster access to important
parts content.
__________________________________________________________
Guideline 8. Orient the user
Checkpoints for content accessibility:
8.1 Make available to the user the author-specified purpose of each
table and the relationships among the table cells and headers.
[Priority 1]
For example, provide information about table headers, how
headers relate to cells, table summary information, cell
position information, table dimensions, etc. Refer also to
checkpoint 5.1. Note. This checkpoint is an important special
case of checkpoint 2.1.
Techniques:
+ Refer to the section on table techniques
+ Allow the user to access this information on demand (e.g., by
activating a menu or keystroke).
The following illustration shows how Internet Explorer provides
cell header information through the context menu:
Internet Explorer context menu item to display table cell
header information
__________________________________________________________
8.2 Indicate to the user whether a link has been visited. [Priority 2]
Note. This checkpoint is an important special case of
checkpoint 8.4.
Techniques:
+ Do not rely on color alone.
+ Refer to techniques for checkpoint 7.3.
+ Refer to the section on link techniques.
__________________________________________________________
8.3 Indicate to the user whether a link has been marked up to indicate
that following it will involve a fee. [Priority 2]
Note. This checkpoint is an important special case of
checkpoint 8.4. "Common Markup for micropayment per-fee-links"
[MICROPAYMENT] describes how authors may mark up micropayment
information in an interoperable manner. This information may be
provided through the standard user interface provided the
interface is accessible. Thus, any prompt asking the user to
confirm payment must be accessible.
Techniques:
+ For a link that has content focus, allow the user to query
the link for fee information.
+ Refer to the section on link techniques.
+ Allow the user to access this information on demand (e.g., by
activating a menu or keystroke for a link).
__________________________________________________________
8.4 Make available to the user information that will help the user
decide whether to follow a link. [Priority 3]
Note. Useful information includes: whether the link designates
an internal or external anchor, the type of the target
resource, the length and size of an audio or video clip that
will be started, and the expected natural language of target
resource.
Techniques:
+ For a link that has content focus, allow the user to query
the link for information.
+ Refer to the section on link techniques.
+ Allow the user to access this information on demand (e.g., by
activating a menu or keystroke).
+ Implement CSS ':visited' and ':link' pseudo-classes, with
':before' class and the 'content' property to insert text
before a link such as "visited" or "un-visited".
The following image shows how the Opera browser allows the user
to configure how links are rendered, including controlling the
rendering of visited and un-visited links.
The Opera dialog box for configuring the rendering of links
__________________________________________________________
Checkpoints for user interface accessibility:
8.5 Provide a mechanism for highlighting and identifying (through a
standard interface where available) the current viewport,
selection, and content focus. [Priority 1]
Note. This includes highlighting and identifying frames. Note.
This checkpoint is an important special case of checkpoint 1.1.
Refer also to checkpoint 8.4.
Techniques:
+ If colors are used to highlight the current viewport,
selection, or content focus, allow the user to set preferred
colors and to ensure sufficient contrasts.
+ If the current viewport is a window, allow the user to cause
the window to pop to the foreground.
+ If the current viewport is a frame or the user doesn't want
windows to pop to the foreground, use colors, reverse videos,
or other visual clues to indicate the current viewport. For
speech or Braille output, render the title or name of a frame
or window and indicate changes in the current viewport.
+ Use operating system conventions, where available, for
specifying selection and content focus (e.g., schemes in
Windows).
+ Implement the CSS pseudo-classes ':hover', ':active', and
':focus'. This will allow users to modify content focus
presentation with user style sheets.
Refer also to the section on frame techniques
The following image illustrates the use by Opera 3.6 of a solid
line border to indicate content focus:
Example of a solid line border used to indicate the content
focus in Opera 3.60
The following image illustrates the use of system highlight
colors to indicate content focus:
Example of system highlight colors used to indicate the content
focus by the accessible browser project
The following image illustrates the use of a dotted line border
to indicate content focus:
Example of dotted line border used to indicate the content
focus in Internet Explorer 5.0 and Netscape Navigator 4.7
__________________________________________________________
8.6 Make available to the user an "outline" view of content, built
from structural elements (e.g., frames, headers, lists, forms,
tables, etc.) [Priority 2]
For example, for each frame in a frameset, provide a table of
contents composed of headers where each entry in the table of
contents links to the header in the document. Note. The outline
view doesn't have to be navigable, but if it is, it may satisfy
checkpoint 7.6.
Techniques:
+ Use commonly understood document models rather than strict
DTD navigation. E.g., properly nesting headers in HTML.
+ For documents that don't use structure properly, user agents
may try to create an outline from presentation elements used
(insufficiently) to convey structure.
+ Allow the user to shrink and expand the outline view
selectively.
+ Provide context-sensitive navigation: for instance, when the
user navigates to a list or table, provide locally useful
navigation mechanisms (e.g., within a table, cell-by-cell
navigation) using similar input commands.
+ Refer to the section on list techniques.
+ Implement a structured view by hiding portions of the
document tree by using the CSS 'display' and 'visibility'
properties ([CSS2], sections 9.2.5 and 11.2, respectively).
The following image shows the table of contents view provided
by Amaya. The table of contents view provided by Amaya can be
navigated and the primary graphical view is synchronized with
the table of contents view, so that the element with the focus
in the table of contents is always in the graphical view.
The table of contents view provided by Amaya
The following technique ideas were provided by the National
Information Standards Organization [NISO]:
A "Navigation Control Center" (NCC) (NCC) resembles a traditional
table of contents, but it is more. The NCC contains links to all
headings at all levels in the book. In addition to the headings,
links to all pages are inserted. Finally we include in the NCC
links to all items that the reader may select to turn off for
reading. For example, if the reader has the automatic reading of
footnotes turned off, there must be a way to quickly get back to
that information. For this reason, the reference to the footnote is
placed in the NCC and the reader can go to the reference,
understand the context for the footnote, and then read the
footnote. All items that have the option of turning off automatic
reading can be reached through the NCC.
Once the reader is at a desired location and wishes to begin
reading, the navigation process changes. Of course, the reader may
elect to read sequentially, but often some navigation is required
(e.g., frequently people navigate forward or backward one word or
character at a time). Moving from one sentence or paragraph at a
time is also needed. This type of local navigation is different
from the global navigation used to get to the location of what you
want to read. It is frequently desirable to move from one block
element to the next. For example, moving from a paragraph to the
next block element which may be a list, blockquote, or sidebar is
the normally expected mechanism for local navigation.
__________________________________________________________
8.7 Provide a mechanism for highlighting and identifying active
elements (through a standard interface where available).
[Priority 2]
Note. User agents may satisfy this checkpoint by implementing
the appropriate style sheet mechanisms, such as link
highlighting.
Techniques:
+ Do not rely on color alone to identify active elements.
+ Use CSS selectors to associate style with elements. In
particular:
o Use CSS link pseudo-classes to highlight links (:link,
:active, :hover).
o Use CSS attribute selectors to match elements with
associated scripts.
+ Allow users to configure highlighting preferences.
__________________________________________________________
8.8 Allow the user to configure the outline view. [Priority 3]
For example, allow the user to configure the level of detail of
the outline. Refer also to checkpoint 8.6. Refer also to
checkpoint 5.2.
Techniques:
For implementations using the CSS 'display' and 'visibility'
properties ([CSS2], sections 9.2.5 and 11.2, respectively),
allow the user to override the default settings in user style
sheets.
Example.
The following CSS 2 style sheet will turn the display off of all HTML
elements inside the BODY element except header elements:
Another approach would be to use class selectors to identify those
elements to hide or display.
End example.
__________________________________________________________
8.9 Allow the user to configure what information about links to
present. [Priority 3]
Note. Using color as the only distinguishing factor between
visited and unvisited links does not suffice since color may
not be perceivable by all users or rendered by all devices.
Refer also to checkpoint 8.4.
Techniques:
+ Allow the user to access this information on demand (e.g., by
activating a menu or keystroke).
+ Implement CSS ':visited' and ':link' pseudo-classes, with
':before' class and the 'content' property to insert text
before a link such as "visited" or "un-visited".
__________________________________________________________
Guideline 9. Notify the user of content and viewport changes
Checkpoints for user interface accessibility:
9.1 Ensure that when the selection or content focus changes, it is in
a viewport after the change. [Priority 2]
For example, users navigating links may navigate to a portion
of the document outside the viewport, so the viewport should
scroll to include the new location of the focus.
Techniques:
+ There are time when the content focus changes (e.g., link
navigation) and the viewport must be moved to track it. There
are other times when the viewport changes position (e.g.,
scrolling) and the content focus is moved to follow it. In
both cases, the focus (or selection) is in the viewport after
the change.
+ Make sure that search windows do not place the new content
focus that is the found object under a search popup.
+ When the content focus changes, "register" the newly focused
element in the navigation sequence; sequential navigation
should start from there.
+ Only change selection/content focus in the current viewport,
not other viewports.
__________________________________________________________
9.2 Prompt the user to confirm any form submission triggered
indirectly, that is by any means other than the user activating
an explicit form submit control. [Priority 2]
For example, do not submit a form automatically when a menu
option is selected, when all fields of a form have been filled
out, or when a mouseover event occurs.
Techniques:
+ Put up a dialog indicating the form will be submitted if it
is done by an onChange, after a certain time, or for other
script-based submission. Allow the user to suppress these
dialogs for good.
+ If the submit button is not the last control in the form, and
no controls after it have been focused, put up a dialog
pointing this out/asking if the user has filled in the
information after the button.
+ If a Javascript submission is fired, allow the user to ask
for it to be intercepted and trigger the dialog mentioned
above.
__________________________________________________________
9.3 Allow the user to configure notification preferences for common
types of content and viewport changes. [Priority 3]
For example, allow the user to choose to be notified (or not)
that a script has been executed, that a new viewport has been
opened, that a pulldown menu has been opened, that a new frame
has received focus, etc.
Techniques:
+ Refer to the section on frame techniques
+ Allow the user to specify an element type for which
notification should be disabled (e.g., table, body, img, ...)
+ Allow the user to disable notification of changes to CSS
properties
+ Allow the user to disable notification of images that are
changed
__________________________________________________________
9.4 When loading content (e.g., document, video clip, audio clip,
etc.) indicate what portion of the content has loaded and
whether loading has stalled. [Priority 3]
Techniques:
Status information - on content loading - should be provided in
a device-independent manner. Techniques include text and
non-text status indicators. Users should be able to request
status information or have it rendered automatically. User
agents may allow users to configure when status information
should be rendered (e.g., by hiding or showing the status bar).
Screen readers may provide access on demand (e.g., through the
keyboard) to the most recent status information, or to announce
the new information whenever it changes.
Useful status information:
+ Document proportions (numbers of lines, pages, width, etc.)
+ Number of elements of a particular type (e.g., tables)
+ The viewport is at the beginning or end of the document.
+ Size of document in bytes.
User agents may allow users to configure what status
information they want rendered. Allow users to access status
information on demand through a keyboard or other shortcut.
Indicate when loading has finished, for example with a
percentage indication or a special message. Indication must not
depend on a particular output device.
__________________________________________________________
9.5 Indicate the relative position of the viewport in content (e.g.,
the percentage of an audio or video clip that has been played,
the percentage of a Web page that has been viewed, etc.).
[Priority 3]
Note. The user agent may calculate the percentage according to
content focus position, selection position, or viewport
position, depending on how the user has been browsing.
Techniques:
+ Provide a scrollbar for the viewport.
+ Give the size of the document as well, so that users may
decide whether to download for offline viewing. For example,
the playing time of an audio file could be stated in terms of
hours, minutes, and seconds. The size of a primarily text
based web page might be stated in both kilobytes and screens,
where a screen of information is calculated based on the
current dimensions of the viewport.
+ List the current "page" as page X of a total of Y pages.
+ Use a variable pitch audible signal to indicate position.
+ Keep the information numerically and generate the output on
user request. See new HTML work on Forms for further examples
(a slider is like a dial is like a menu of lots of
options...)
+ Provide standard markers for specific percentages through the
document (mile posts)
+ Provide markers for positions relative to some position - a
user selected point, the bottom, the H1, etc.
+ Put a marker on the scrollbar, or a highlight at the bottom
of the page while scrolling (so you can see what was the
bottom before you started scrolling
__________________________________________________________
Guideline 10. Allow configuration and customization
Checkpoints for user interface accessibility:
10.1 Provide information to the user about current user preferences
for input configurations (e.g., keyboard or voice bindings).
[Priority 1]
Techniques:
If the currently active configuration changes locally (e.g., a
search prompt opens, changing the keyboard mapping for the
duration of the prompt), alert the user. The user must also be
informed of the changed (currently active) configuration. Do
not rely on visual or audio cues alone to alert the user of the
change. Do not limit the user to only one type of alert
mechanism. Do not rely on visual cues (e.g., the underlining of
an accelerator key) alone to inform the user of changes in the
configuration.
Named configurations are easier to remember. This is especially
important for persons with certain types of cognitive
disabilities. For example, if the invocation of a search prompt
changes the currently active configuration, the user may
remember more easily which keystrokes are active in search mode
if alerted that there is a "Search Mode". Context-sensitive
help (if available) should reflect the change in mode, and a
list of keybindings for the current mode should be readily
available to the user.
2.10.1 Documentation of sequential navigation order
+ Specified by the HTML 4.0 "tabindex" attribute ([HTML40],
section 17.11.1).
+ Provide a list of form controls according to the sequential
navigation order of the form. This allows users to know
whether, for example, a submit button is the last control in
a form or whether the user must activate controls that follow
it.
+ Provide a structured view of form controls (e.g., those
grouped by LEGEND or OPTGROUP in HTML) along with their
labels.
2.10.2 Documentation of keyboard shortcuts
+ Specified by the HTML 4.0 "accesskey" attribute ([HTML40],
section 17.11.2).
+ Use system conventions to indicate the current configuration.
+ Document the default configuration.
+ Allow direct navigation to active elements (links, form
controls, etc.). For instance, through a menu that allows
users to enter a link number of link text and to move the
content focus there.
+ Allow the user to separate setting the content focus and
activating the control. For links, first-time users of a page
may want to hear link text before deciding whether to follow
the link (activate). More experienced users of a page would
prefer to follow the link directly, without the intervening
content focus step.
2.10.3 Configuration of the user interface
+ Allow the user to configure the user agent so that the
current viewport is automatically maximized. For example, the
parent window of the browser would automatically be maximized
when launched, and each child window would automatically be
maximized when it received focus. Maximizing does not
necessarily mean occupying the whole screen or parent window;
it means expanding the current window so that the need to
scroll horizontally or vertically is as little as possible.
__________________________________________________________
10.2 Avoid default input configurations that interfere with operating
system accessibility conventions. [Priority 1]
In particular, default configurations should not interfere with
the mobility access keyboard modifiers reserved for the
operating system. Refer also to guideline 5.
10.3 Provide information to the user about current author-specified
input configurations (e.g., keyboard bindings specified in
content such as by "accesskey" in HTML 4.0). [Priority 2]
Techniques:
+ Make a list of keybindings for the currently rendered page
available to the user. If any of the author-defined
keybindings conflict with application or OS keybindings,
alert the user in a device independent manner. Do not, for
example, rely exclusively on font or color changes, on the
playing of an audio clip, or upon an icon to convey this
information to the user.
+ In case of conflicts between author-supplied configuration
and user-supplied, operating system defaults, or user agent
default configurations, here is some possible behavior:
1. Do not override default system and UA controls, but
alert the user if author-supplied keybindings conflict
with them, and provide a pass-through mechanism to allow
the user to invoke author-specified UI controls that
conflict with default UA or OS controls/keybindings.
2. Allow author-defined keybindings to over-ride UA and OS
keybindings, but alert the user of the conflicts, and
provide a pass-through mechanism so that the conflicting
UA / OS keybindings can still be invoked.
3. Allow the user to choose to have the UA re-map
author-supplied keybindings to currently unused
keystrokes, then alert the user to which keystrokes the
author-supplied UI controls / keybindings have been
re-mapped.
It is probably useful to distinguish the following classes of
user input configurations:
+ What are the defaults "out of the box"?
+ What are the current settings different from those out of the
box.
+ What are those in effect for the current document only?
+ What are those that have been overridden by the configuration
of the current document? Also, how to access functionalities
no longer available due to the current input configuration.
In association with local (e.g., "this page only") and
off-default bindings, provide information about how to work
around the override.
Note that user support personnel, particularly remote support
personnel, will need the "departures from shipping defaults"
view for orientation.
The above classes may be distinguished by displayed properties
in a combined presentation as well as by filtering to present
only a restricted class.
Some reserved keyboard shortcuts are listed in the appendix on
accessibility features of some operating systems.
__________________________________________________________
10.4 Allow the user to change the input configuration. [Priority 2]
For voice-activated browsers, allow the user to modify what
voice commands activate functionalities. Similarly, allow the
user to modify the graphical user agent user interface for
quick access to commonly used functionalities (e.g., through
buttons).
Techniques:
Provide a convenient interface for allowing users to change
input configurations. For example, allow them to select some
pre-configured options rather than having them enter
combinations themselves. This will speed up configuration and
reduce questions to support staff later on how to configure the
user agent.
User agents that allow users to customize or reconfigure
mappings from keyboard, voice, etc. to user agent
functionalities should allow each mapping to be accompanied by
a description so that the user can understand the mapping. For
example, if "Control-P" maps to a print functionality, a short
description would be "Print" or "Print setup".
+ Profiles
+ Default values
+ Device-independent configuration
When using a physical keyboard, some users require single-key
access, others require that keys activated in combination be
physically close together, while others require that they be
spaced physically far apart. When allowing users to configure
keyboard access to functionalities, user agents must consider
operating system conventions, author-specified shortcuts, and
user preferences. The user agent's default configuration should
include shortcuts for frequently performed tasks and should
respect operating system conventions.
User agents, to allow the user to turn on and off
author-specified keyboard configurations, may offer a checkbox
in the keyboard mapping dialog to that would toggle the support
for author-specified keyboard configurations. In HTML 4.0,
authors may specify keyboard behavior with the "tabindex" and
"accesskey" attributes ([HTML40], sections 17.11.1 and
17.11.2, respectively).
Allow users to restore easily the user agent's default
configuration.
Allow users to create macros and bind them to keystrokes or
other input methods.
2.10.4 Configuration of activation method
When the author specifies a keyboard shortcut (e.g., with
"accesskey" in HTML), only the shortcut key is defined. It is
left to the user agent to apply a triggering mechanism that
will invoke the shortcut key. For example, Microsoft Internet
Explorer 5 uses the ALT key as the trigger key when running on
the Windows platform. This triggering mechanism, however,
conflicts with some default OS and application keybindings that
also rely upon the ALT key for their triggering mechanism, such
as ALT+F (the keybinding that invokes the "File" menu) and
ALT+H (the keybinding that invokes the "Help" menu).
Until a W3C Recommendation or some other specification explains
how to resolve conflicts, user agents may resolve them by
allowing users to choose from among several triggering
mechanisms for keyboard shortcuts. The user agent can ask the
user to choose a shortcut trigger, and warn the user of
potential conflicts (e.g., through context sensitive help, a
"More Information" button, a field label, explanatory text in a
.cfg file, etc.). While the interactivity level of such a
mechanism is best left to individual developers to define, a
basic definition request could take a form similar to the
following, platform-specific, example:
Please choose triggering mechanism for shortcut keys. Some shortcut
keys are specified by authors so that you may activate a link, move
through a page, or activate form controls using a keystroke
combination. Half of the combination (an alphabetic or numeric
character) is pre-defined by the author. In order to trigger the
shortcut key, however, you must select a "trigger key", which --
when pressed in conjunction with the shortcut key -- will activate
the associated element. It is highly recommended that you do not
use the ALT or CONTROL keys for the trigger, as they are commonly
used to trigger application and system events in the Windows
environment.
This type os mechanism/message might be presented to the user
the first time that a page with author-specified shortcut keys
is loaded. Such a mechanism should also form part of the
general configuration mechanism for the user agent.
Ensure uniform behavior when a shortcut key is invoked. Provide
the user with the following options:
1. move focus to the element for which the shortcut key has been
defined.
2. activate the element for which the shortcut key has been
defined
3. prompt the user each time an shortcut key is invoked. Note.
The prompt should also allow the user to "Save current choice
as the default action for the shortcut key X")
__________________________________________________________
10.5 Allow the user to configure the user agent so that the user's
preferred one-step operations may be activated with a single
input command (keystroke, voice command, etc.). [Priority 2]
Note. User agents are not required to provide single command
activation of all user agent functionalities at once, only some
of them. This checkpoint is an important special case of
checkpoint 10.4
Techniques:
To illustrate problems some users with poor physical control
encounter and why single-key access is important: Put the
keyboard Repeat Delay to very short and the Repeat rate to very
fast (or whatever rate is bothersome). The slightest touch or
accidental bump will generate a key press, illustrating the
challenge key combinations pose.
In keyboard-driven browsing the page control keys just right of
ENTER are important so the Web navigation keys should be around
ENTER [which gets a link]. The enhanced keyboard is huge for
anyone using just 1 digit, be it head or hand; and key
combinations add tiring, extra work while individual keys go
unused. Example: SHIFT-TAB to get the previous Anchor means 2
keystrokes which is hard as I'm unsteady (To get an idea of
what how some folks work put the keyboard Repeat Delay to very
short and Repeat rate to very fast, key combinations become a
huge challenge, to say the least) and apt to miss the desired
link so it can take 4 keystrokes to pick a link. Just as Page
Up and Down are paired on the Keypad area Web navigation
controls must be paired on the main keyboard (Less movement
around keyboards helps folks with muscle degeneration as they
tend to have slow or reduced mobility).
Opera uses the main alphanumeric key area of keyboards to make
all common browser commands single-key commands. The software
keyboard Mouse, "Mouse Keys" (which turns NumPad into
single-key mouse commands), is a prime example of using
keyboards in a different manner to give people with physical
disabilities a usable command structure. Moreover "Mouse Keys"
proves that such innovation doesn't interfere with expected use
by users who don't need single-key configurations because it
can be turned on and off, or time-out itself.
Some pairs include move Anchor highlight up and down and next
page and back to previous page. Vertical or horizontal pairing
might provide a cue about what movement occurs, perhaps a UI
designer could comment. BACKSPACE for page back and the "=" key
for page ahead. The "[" key for Anchor up and ";" key for down
[this is only for links]. Form boxes should be selected via TAB
and SHIFT-TAB, for limited use a key combo is fine because it
actually lessens chances users get into an unwanted mode. Using
O or Zero seems too confusing so lets use 9 for Previous Frame
and I as Next Frame [and Anchor movements should cycle within a
Frame, not the whole page]. DHTML Layers K as Up and "," as
Down with U to Activate events. The 9, I, K, and "," keys are
roughly in line vertically yet key rows are offset so its
harder to slide up or down then left or right, where the sides
of keys fully in line making a mistaken push easier. Because
Frames and Layers divide pages up it would help if browsers
used sound files to say Frames and/or Layers are on a page.
Moving between HTML Headings hasn't been too helpful as many
Web pages are non-linear so Headings doesn't resemble Page-Down
command to get to a lower sub-section, H and N will do.
__________________________________________________________
10.6 Follow operating system conventions to indicate the input
configuration. [Priority 2]
For example, on some operating systems, if a functionality is
available from a menu, the letter of the key that will activate
that functionality is underlined. Note. This checkpoint is an
important special case of checkpoint 5.6.
Techniques:
In some operating systems, information about shortcuts is
rendered visually using an underscore under a character in a
menu item or button corresponding to the shortcut key activated
with an ALT+character. For menu accelerators the text in the
menu item is often followed by a CNTRL+function key. These are
conventions used by the Sun Java Foundations Classes [JAVA-TUT]
and Microsoft Foundations Classes for Windows.
__________________________________________________________
10.7 Allow the user to configure the user agent through a profile.
[Priority 2]
Users must be able to select from among available profiles or
no profile (i.e., the user agent default settings).
Techniques:
Configuration profiles allow individual users to save their
user agent settings and re-apply them easily. This is
particularly valuable in an environment where several people
may use the same machine. Profiles may include rendering
preferences as well as user email address, proxy information,
stylesheet preferences, etc.
The user should be able to easily transfer profiles between
installations of the same user agent (e.g., over the network).
One way to facilitate this is to follow applicable operating
system conventions for profiles.
Users should be able to switch rapidly between profiles (or the
default settings) and to set a new default profile. This is
helpful when:
+ Several people use the same machine.
+ One user is being helped by another who may not recognize the
information being displayed using the user's profile.
User agents may apply a profile when the user logs in. They may
also allow users to apply settings interactively, for example
by allowing them to choose from a list of named profiles in a
menu.
Sample profiles (based on common usage scenarios) can assist
users in the initial set up of the user agent. These profiles
can serve as models and may be copied and fine-tuned to meet an
individual's particular needs.
Cascading Style Sheets may be part of a source document or
linked externally. Stand-alone style sheets are useful for
implementing user profiles in public access computer
environments where several people use the same computer. User
profiles allow for convenient customization and may be shared
by a group.
A text profile may be pasted in email and is useful for
technical support purposes.
Provide compatibility modes for users who require a familiar
user interface. For instance, let the user choose from a list
of default input configurations from preceding versions of the
software.
__________________________________________________________
10.8 Provide default input configurations for frequently performed
tasks. [Priority 3]
Make the most frequent operations easy to access, and operable
through a single command. In particular, provide convenient
mappings to functionalities that promote accessibility such as
navigation of links. Functionalities include being able to
show, hide, resize and move graphical viewports created by the
user agent.
Techniques:
+ Make available different profiles.
+ Test the default keyboard configuration for usability. Ask
users with different disabilities and combinations of
disabilities to test configurations.
+ For people using one hand, a few fingers, or a headwand
pointer, access to important functionalities must be
available through one or at most two key presses.
+ Avoid deeply nested menus.
+ Allow users to accomplish tasks through repeated keystrokes
(e.g., sequential navigation) since this means less physical
repositioning for all users.
+ However, repeated keystrokes may not be efficient for some
tasks. For instance, do not require the user to position the
pointing device by pressing the "down arrow" key repeatedly.
+ Input configurations should allow quick and direct navigation
that does not rely on graphical output. Do not require the
user to navigate through "space" (through a graphical user
interface) as the only way to activate a functionality.
__________________________________________________________
10.9 Allow the user to configure the arrangement of graphical user
agent user interface controls. [Priority 3]
Techniques:
+ Allow multiple icon sizes (big, small, other sizes).
+ Allow the user to choose icons and/or text
+ Allow the user to change the grouping of icons
+ Allow the user to show and hide controls. This can benefit
users with cognitive disabilities and also make life easier
for users who have to navigate them sequentially.
+ Allow the user to change the position of control bars, icons,
etc. Do not rely solely on drag-and-drop for reordering tool
bar; the user must be able to configure the user agent user
interface in a device-independent manner (e.g., through a
text-based profile).
__________________________________________________________
Guideline 11. Provide accessible product documentation and help
Checkpoints for user interface accessibility:
11.1 Provide a version of the product documentation that conforms to
the Web Content Accessibility Guidelines. [Priority 1]
User agents may provide documentation in many formats, but at
least one must conform to the Web Content Accessibility
Guidelines [WAI-WEBCONTENT]. Equivalent alternatives for
content, navigation mechanisms, and illustrations will all help
make the documentation accessible.
Techniques:
It is essential that any web-based support and/or documentation
that is produced or maintained by the manufacturer of a user
agent or by a sub-contractor of the user agent's developer,
conform to the Web Content Accessibility Guidelines
[WAI-WEBCONTENT]. This includes (but is not limited to):
1. text equivalents of all graphics
2. extended descriptions of screen-shots, flow-charts, etc.
3. clear and consistent navigation and search mechanisms
4. use of the NOFRAMES element when the support/documentation is
presented in a FRAMESET
5. serial listings of keystrokes and keybindings
Accessing documentation in familiar applications is
particularly important to users with disabilities who must
learn the functionalities of their tools and be able to
configure them for their needs. Commonly used applications are
also more likely to be compatible with assistive technology.
Electronic documentation should not be provided in proprietary
formats.
Where possible, allow users to download documentation in a
single block (e.g., single HTML file, zip archive of several
HTML and image files, etc.)
Run-time help and any Web-based help or support information, as
well as the documentation distributed with the tool, must be
fully accessible to persons with disabilities. Per checkpoint
1.1, the user must be able to invoke the run-time help with a
simple, well documented keystroke command. It is strongly
suggested that the keybinding used to invoke the UAs help
system be the default "Help" keybinding for the operating
system.
Users with print disabilities may need or desire documentation
in alternative formats such as Braille (refer to "Braille
Formats: Principles of Print to Braille Transcription 1997"
[BRAILLEFORMATS]), large print, or audio tape. User agent
manufacturers may provide user manuals in alternative formats.
Documents in alternative formats can be created by agencies
such as Recording for the Blind and Dyslexic and the National
Braille Press.
User instructions should be expressed in an input device
independent manner. Provide instructions for using or
configuring the user agent in a manner that can be understood
by a user of any input device including a mouse or keyboard.
For example, "Select the Home button on the toolbar" or "Select
Home from the Go menu to return to the Home page."
Universal design means that access to features that help
accessibility should be integrated into standard menus. User
agents should avoid regrouping access to accessibility features
into specialized menus.
Proper documentation is important to developers with
disabilities, not just users with disabilities. A disabled user
may be a developer using the user agent as a test bed or
someone who needs critical information that can only be
obtained by as direct a path to the tool's mechanics and
"under-the-hood" features as possible. Detailed accessible
documentation (e.g., distributed on CD-ROM) is important to
allow assistive technology developers access to APIs, etc.
Ensure that product identification codes are accessible to
users so they may install their software. Codes printed on
product cases will not be accessible to people with visual
disabilities.
__________________________________________________________
11.2 Document all user agent features that promote accessibility.
[Priority 1]
For example, review the documentation or help system to ensure
that it includes information about the functionalities
addressed by the checkpoints of this document.
Techniques:
Include references to accessibility features in these parts of
the documentation:
1. Indexes. Include terms related to product accessibility in
the documentation index (e.g., "accessibility", "disability"
or "disabilities").
2. Tables of Contents. Include terms related to product
accessibility in the documentation table of contents (e.g.,
features that promote accessibility)
3. Include instructions on how to modify all user configurable
defaults and preferences (e.g, images, video, style sheets,
and scripts) as specified by the documentation.
4. Include a list of all keyboard shortcuts or other input
configuration information in the accessibility section of the
documentation.
5. Document the features implemented to conform with these
Guidelines.
Accessibility features should be presented as such, not hidden
under other topics. For instance, users (especially novice
users) should be able to look up "How to turn off blinking
text" in the documentation. Even if the solution for turning
off blinking text is to turn off scripts, users should not have
to guess that turning off scripts will disable blinking text.
The user interface should also be designed so that
accessibility topics are presented as such.
__________________________________________________________
11.3 Document the default input configuration (e.g., default keyboard
bindings). [Priority 1]
Techniques:
Here is a table showing mappings between Netscape Navigator
functions (or potential functions) and their keyboard shortcuts
in Macintosh, Unix, and Windows versions. If a function exists
in the browser but does not have a shortcut, its corresponding
cell is marked with an asterisk(*). If the function does not
exist, it is left blank. Note. This table lists some, but not
all, functionalities and keyboard shortcuts of Netscape
Navigator. It is meant to illustrate, not serve as definitive
documentation.
Some entries contain links to special notes. The number in
parentheses following the link is the number of the relevant
note.
Linear version of of Netscape Navigator Keyboard Shortcuts.
CAPTION: Netscape Navigator Keyboard Shortcuts
Function Macintosh (v 4.61) Unix (v 4.51) Windows (v 4.7)
Move within a document
Scroll to next page Page Down Page Down Page Down
Scroll to previous page Page Up Page Up Page Up
Scroll to top * * Ctrl-Home
Scroll to bottom * * Ctrl-End
Move between documents
Open a new document Command+L Alt+O Ctrl+O
Stop loading a document Command+. Esc Esc
Refresh a document Command+R Alt+R Ctrl+R
Load previous document Command+[
or
Command+Left Arrow Alt+Left Arrow Alt+Left Arrow
Load next document Command+]
or
Command+Right Arrow Alt+Right Arrow Alt+Right Arrow
Navigate elements within a document
Move focus to next frame * * *
Move focus to previous frame * * *
Move focus to next active element (1) Tab Tab Tab
Move focus to previous active element (1) Shift+Tab Shift+Tab
Shift+Tab
Find word in page Command+F Alt+F Ctrl+F
Act on HTML elements
Select a link * * Enter
Toggle a check box * * Shift or Enter
Activate radio button * * Shift
Move focus to next item in an option box * * Down Arrow or Right Arrow
Move focus to previous item in an option box * * Up Arrow or Left
Arrow
Select item in an option box * * Enter
Press a button (2) Return Enter Enter
Navigate menus
Activate menu * * Alt+ the underlined letter in the menu title
Deactivate menu * Esc Esc
Move focus to next menu item * * (3) Down Arrow
Move focus to previous menu item * * (3) Up Arrow
Select menu item * underlined letter in the menu item Enter
Move focus to submenu * * (3) Right Arrow
Move focus to main menu * * (3) Left Arrow
Navigate bookmarks
View bookmarks menu * (4) * Alt+C+B
Move focus to next item in bookmarks menu Down Arrow (4) * Down Arrow
Move focus to previous item in bookmarks menu Up Arrow (4) * Up Arrow
Select item in bookmarks menu Return (4) * Enter
Add bookmark Command+D Alt+K Ctrl+D
Edit bookmarks Command+B Alt+B Ctrl+B
Delete current bookmark (5) Delete Alt+D Delete
Navigate history list
View history list Command+H Alt+H Ctrl+H
Move focus to next item in history list * * Down Arrow
Move focus to previous item in history list * * Up Arrow
Move focus to first item in history list * * Left Arrow
Select item in history list * * Enter (6)
Close history list Command+W Alt+W Ctrl+W
Define view
Increase font size (7) Shift+Command+] Alt+] Ctrl+]
Decrease font size (7) Shift+Command+[ Alt+[ Ctrl+[
Change font color * * *
Change background color * * *
Turn off author-defined style sheets * * *
Turn on user-defined style sheets (8) ? ? ?
Apply next user-defined style sheet ? ? ?
Apply previous user-defined style sheet ? ? ?
Other functionalities
Access to documentation * * *
Notes.
1. In Windows, active elements can be links, text entry boxes,
buttons, checkboxes, radio buttons, etc. In Unix and
Macintosh, Tab cycles through text entry boxes only.
2. In Windows, this works for any button, since any button can
gain the user interface focus using keyboard commands. In
Unix and Macintosh, this only applies to the "Submit" button
following a text entry.
3. In Unix, the menus can not be opened with shortcut keys.
However, once a menu is opened it stays opened until it is
explicitly closed, which means that the menus can still be
used with shortcut keys to some extent. Sometimes left and
right arrows move between menus and up and down arrows move
within menus, but this does not seem to work consistently,
even within a single session.
4. In Macintosh, you can not explicitly view the bookmarks menu.
However, if you choose "Edit Bookmarks", which does have a
keyboard shortcut, you can then navigate through the
bookmarks and open bookmarked documents in the current
window.
5. To delete a bookmark you must first choose "Edit Bookmarks"
and then move the focus to the bookmark you want to delete.
6. In Windows, when you open a link from the history menu using
Enter, the document opens in a new window.
7. All three systems have menu items (and corresponding shortcut
keys) meant to allow the user to change the font size.
However, the menu items are consistently inactive in both
Macintosh and Unix. The user seems to be able to actually
change the font sizes only in Windows.
8. It is important to allow users to set their own cascading
style sheets (css). Although Netscape does currently allow
the user to override the author's choice of foreground color,
background color, font, and font size, it does not allow some
of the advanced capabilities that make cascading style sheets
so powerful. For example, a blind user may want to save a
series of style sheets which show only headers, only links,
etc., and then view the same page using some or all of these
style sheets in order to orient himself to the contents and
organization of the page before reading any of the actual
content.
__________________________________________________________
11.4 In a dedicated section of the documentation, describe all
features of the user agent that promote accessibility.
[Priority 2]
Note. This is a more specific requirement than checkpoint 11.2.
Techniques:
In the documentation for each product feature, include
information about accessibility. In an easy-to-find section on
accessibility features, list all features that promote
accessibility and link to them. A dedicated section documenting
the features of the user agent that promote accessibility,
however, should not be the only method of documenting such
features.
__________________________________________________________
11.5 Document changes between software releases. [Priority 2]
Techniques:
+ Document changes to the user interface.
+ At a minimum provide a text description of changes (e.g., in
a README file).
__________________________________________________________
_________________________________________________________________
3 Accessibility Topics
This section introduces some general techniques to promote
accessibility in user agent functionality. A list of assistive
technologies and browsers [USERAGENTS] designed for accessibility is
available at the WAI Web site.
3.1 Access to content
Users must have access to document content, however they are browsing.
Content can come from:
* the document source, both primary content and equivalent
alternatives. Document source includes element content, attribute
values, and referenced content (e.g., images).
* style sheets.
* the user agent.
The most basic way to give users access to content is to render the
entire document in one stream, whether it be a two-dimensional
graphical layout, audio stream, or line-by-line Braille stream).
However, user agents should do much more to ensure that users can
understand a page by:
* Preserving structure when rendering
* Allowing the user to select specific content and query its
structure or context
* Allowing access to equivalent alternatives of content.
* Using and generating metadata to provide context
* Allowing the user to configure the user agent for different
rendering options
These topics are addressed below.
3.1.1 Preserve and provide structure
Retain structure when rendering. For example, a graphical rendering of
tables conveys relationships among cells. Serial renderings (e.g., to
speech) must also make those relationships apparent, otherwise users
will not know where a table cell ends, or a list item, etc. One
technique for maintaining structure is to precede content with
"header" information (upon user demand). For example, give the
position of a table cell or it's associated headers. Or indicate the
position of a list item within nested lists.
Provide "intelligent" structure that may not be exactly what the DTD
says. For instance, in HTML, header elements do not nest, but
presenting the document as hierarchical may give users a better sense
of document structure. Use common idioms where known, even if they are
not expressly in the DTD.
3.1.2 Allow access to selected content
In the Amaya browser [AMAYA], users may access attribute values as
follows: Place the cursor at the element in question, open/swap to the
structure view. You are shown list of attributes and values. Another
technique: select the element (press escape in Linux), then the
attributes are all available from the attributes menu. For "alt", one
can also look at the alternate view, which renders text equivalents
instead of images - a lynx-like view. All the views are synchronized
for navigation (and for editing).
Users may want to select content based on the rendering structure
alone (i.e., that amounts to selecting across element borders).
Users may want to select content based on structure (e.g., a table
cell). Amaya allows users to "climb" the document tree by positioning
the cursor and pressing the Escape key. Each Escape selects one node
higher in the document tree, up to the root.
3.1.3 Access to equivalent alternatives of content
Speech-based user agents providing accessible solutions for images
should, by default, provide no information about images for which the
author has provided no text equivalent. The reason for this is that
the image will clutter the user's view with unusable information
adding to the confusion. In the case of an speech rendering, nothing
should be spoken for the image element. This user should be able to
turn off this option to find out what images were inaccessible so that
the content author could be contacted to correct the problem.
In the case of videos, an assistive technology should, by default,
notify the user that a video exists as this will likely result in the
launch of a plug-in. In the case of a video, user agents should
indicate what type of video it is, accompanied by any associated
equivalent alternative. User agents should prefer plug-ins that
support system-specific accessibility features over those that don't.
In the case of applets, an assistive technology should, by default,
notify the user that an applet exists, as this will likely result in
the launch of an associated plug-in or browser specific Java Virtual
Machine. In the case of an applet, the notification should include any
associated equivalent alternatives. This is especially important since
applets typically do provide an application frame that would provide
application title information.
When an applet is loaded, it should support the Java system
conventions for loading an assistive technology (refer to the appendix
on loading assistive technologies for DOM access). When the applet
receives content focus, the browser user agent should first notify the
user about the applet as described in the previous paragraph and turn
control over to the assistive technology that provides access to the
Java applet.
Suppose an object with a preferred geometry is specified and not
rendered, should the equivalent alternative be rendered in the
preferred (but empty) region? What if the equivalent alternative
exceeds the size of the preferred geometry? One option is to allow the
user to specify through the UI whether to respect the preferred
geometries or ignore them.
For information about equivalent alternatives for SMIL content, refer
to "Accessibility Features of SMIL" [SMIL-ACCESS].
In HTML 4.0 [HTML40], authors supply equivalent alternatives for
content as follows:
* For the IMG element (section 13.2): The "alt" (section 13.8),
"title" (section 7.4.3), and "longdesc" (section 13.2)
attributes.
* For the OBJECT element (section 13.3): The content of the element
and the "title" attribute.
* For the deprecated APPLET element (section 13.4): The "alt"
attribute and the content of the element.
* For the AREA element (section 13.6.1): The "alt" attribute.
* For the INPUT element (section 17.4): The "alt" attribute.
* For the ACRONYM and ABBR elements (section 9.2.1): The "title"
attribute may be used for the acronym or abbreviation expansion.
* For the TABLE element (section 11.2.1), the "summary" attribute.
* For frames, the NOFRAMES element (section 16.4.1) and the
"longdesc" attribute (section 16.2.2) on FRAME and IFRAME
(section 16.5).
* For scripts, the NOSCRIPT element (section 18.3.1).
3.1.4 Missing equivalent alternatives of content
* The "Altifier Tool" [ALTIFIER] illustrates smart techniques for
generating text equivalents for images, etc. when the author
hasn't supplied any.
* If no captioning information is available and captioning is turned
on, render "no captioning information available" in the captioning
region of the viewport.
3.1.5 Context
In addition to providing information about content, user agents must
provide contextual information. For example:
* table cell row/column position
* table cell header information.
* Nested list item numbers
* Content language
User agents can use style sheet languages such as CSS 2 [CSS2] and
XSLT [XSLT] to generate contextual information.
Example.
The following XSLT style sheet (taken from the XSLT Recommendation
[XSLT], Section 7.7) shows how to one might number H4 elements in
HTML with a three-part label:
..
End example.
3.2 User control of style
To ensure accessibility, users must have final control over certain
renderings.
* For changing text size, allow font size changes or provide a zoom
mechanism.
* To hide content, use the CSS 'display' and 'visibility' properties
([CSS2], sections 9.2.5 and 11.2, respectively).
Implement CSS ([CSS1], [CSS2]) including the CSS 2 cascade order
(section 6.4.1) and user style sheets. The CSS 2 cascade order ensures
that user style sheets with "!important" (section 6.4.2) take
precedence over author styles, giving users final control. Style
sheets give authors design flexibility while offering users final
control over presentation (refer also to Web Content Accessibility
Guidelines 1.0 checkpoint 3.3 ([WAI-WEBCONTENT]). CSS should be
implemented by user agents that implement CSS for text that it
renders. CSS includes properties for audio, Braille (fixed and
refreshable), screen, and print rendering, and all relevant properties
for supported output media should be implemented.
Note that in the CSS cascade order, markup is given less weight than
style sheet rules. Thus, an author may use both presentation markup
and style sheets, and user agents that support style sheets will
prefer the latter.
A user style sheet can be implemented through the user agent user
interface, which means that the user may not have to understand how to
write style sheets; they are generated or the user agent acts as
though they were. For an example of this, refer to the style sheets
implementation of Amaya [AMAYA], which provides a GUI-based interface
to create and apply internal style sheets. The same technique could be
used to control a user style sheet.
For images, applets, and animations:
Background images may be controlled by the use of local style sheets,
and more effectively if these can be dynamically updated. Animation
rate depends on the players used. User agents that provide native
rendering of animation (for example a movie player, a driver for
animated GIF images, or a java machine) should enable the control of
animation rates, or at least allow the user to stop, and to play
frame-by-frame, as well as straight rendering. A user agent could
provide control of the general timing of a presentation, combined with
the ability to select from available tracks manually. An issue to bear
in mind is that when animation is synchronized with audio, a user may
need the ability to play the animation separately from the associated
audio.
For time-based presentations:
Implement user controls to start, atop, rewind and pause
presentations, and where multiple tracks are supported, to choose
which tracks should be rendered. SMIL 1.0 [SMIL] provides for a number
of these features. A SMIL implementation should provide for direct
user control, as well as activation of the controls through a
published API, for developers of assistive technologies.
For user agents rendering audio:
On selecting from among available description tracks. SMIL 1.0 [SMIL]
allows users to specify captions in different languages. By setting
language preferences in the SMIL player, users may access captions (or
audio) in different languages.
The G2 player from Real Networks currently allows users to specify
which language they prefer, which can be evaluated in a SMIL document
to choose from among text or auditory tracks. Currently only one
language can be indicated which does not permit choosing, for example,
English spoken audio with Spanish captions.
The Quicktime player currently permits turning on and off any number
of tracks individually, which can include audio, video, and text.
For user agents rendering video:
Implement the CSS positioning and/or SMIL layout languages. Allow the
user to freeze a presentation, manually move and resize component
visual tracks (including captions, subtitles and signed translations)
and to apply CSS stylesheets to text-based presentation and SVG.
For user agents rendering speech:
CSS 2 aural style sheet properties ([CSS2], section 19) can allow
users to configure speech rate, volume, and pitch. These can be
implemented by allowing the user to write and apply a local style
sheet, or can be automatically generated by means of (accessible) user
controls, which should also be controllable through an API.
User interface:
* Allow the user to select large or small buttons and controls (and
ensure that these values are applied consistently across the user
interface)
* Allow the user to control features such as menu font sizes, or
speech rates - this may be achieved through use of operating
system standards.
* Allow the user to regroup buttons and controls, and reorder menus.
3.3 Link techniques
* Address broken link handling so that it doesn't disorient users.
For example, leave the viewport as is and notify user.
* Provide the user with media-independent information about the
status of a link as the link is chosen. For example, do not rely
solely on font styles or color changes to alert the user whether
or not the link has previously been followed. The user should be
able to pick from amongst a list of alert mechanisms (i.e. color
changes, sound clips, status line messages, etc.), and should not
be limited to only one type of alert mechanism.
+ For assistive technologies: Provide the user with the option
to have the "title" (if present) or the hyperlink text made
available to the user when the user navigates from link to
link.
* Alert the user if following a link involves the payment of a fee.
* When presenting the user with a list of the hyperlinks contained
in a document, allow the user to choose between "Display links
using hyperlink text" or "Display links by title (if present)",
with an option to toggle between the two views. For a link without
a title, use the link text.
+ Provide the user with orientation information about the
listed links. For example, identify a selected link as "Link
X of Y", where "Y" is the total number of links available in
the document.
* Offer the user a list of links which have been visited and a list
of links which have not yet been visited, or provide a
media-independent mechanism to distinguish between visited and
unvisited links. Do _not_ rely on visual or aural prompts alone to
signify the difference between visited and unvisited links.
* Offer the user a list of links which are internal (i.e., local to
document) and those which are external, or provide a
media-independent mechanism to distinguish between external and
internal links in a list of links. Do not rely on visual or aural
prompts *alone* to signify the difference between internal and
external links.
* Use the CSS2 ':before' pseudo-elements ([CSS2], section 5.12.3) to
clearly indicate that something is a link (e.g., 'A:before {
content : "LINK:" }').
* Implement the CSS pseudo-class ':hover'.
Lynx allows the user to choose from the following options for images
without "alt" supplied:
* Insert a generic placeholder (e.g., [IMAGE]) in place of the
image.
* Insert the file name in place of the image.
* Render nothing.
The same technique might be used when "alt" is supplied but whitespace
only. However, if an image with empty or whitespace "alt" text is part
of a link:
* Insert a generic placeholder (e.g., [LINK]) in place of the image.
* If supplied for the link element, render the "title" attribute.
* Otherwise, if the link designates an HTML document, use the
content of the TITLE element in that document as link text.
* Otherwise render the filename or URI of the designated resource.
Lynx [LYNX] numbers each link and other element and provides
information about the relative position of the section of the
document. Position is relative to the current page and the number of
the current page out of all pages. Each page usually has 24 lines.
Information about link status and other properties can be provided in
an information view such as that provided by Netscape Navigator about
how many and what types of elements are in a document.
User agents should not consider that all local links (to anchors in
the same page) have been visited when the page has been visited.
User agents may use graphical or aural icons to indicate visited links
or broken links.
Users should be able to:
* Configure what information about links they wish presented to
them.
* Turn on and off automatic rendering of this information when a
link receives content focus.
* Get information about a link on demand, even if automatic
rendering has been turned off.
Jaws for Windows offers a view for configuring a number of rendering
features, notably some concerning link types, text link verbosity,
image map link verbosity, graphical link verbosity, and internal
links:
Jaws for Windows HTML Options menu, which allows configuration of a
number of link rendering options
3.4 List techniques
Ordered lists help non-visual users navigate. Non-visual users may
"get lost" in lists, especially in nested lists and those that do not
indicate the specific nest level for each list item. Until user agents
provide a means to identify list context clearly (e.g., by supporting
the ':before' pseudo-element in CSS2), content developers should
include contextual clues in their lists.
For numbered lists, compound numbers (or letters, numbers, etc.) are
more informative than simple numbers. Thus, a list numbered "1, 1.1,
1.2, 1.2.1, 1.3, 2, 2.1," provides more context than the same list
without compound numbers, which might be formatted as follows:
1.
1.
2.
1.
3.
2.
1.
and would be spoken as "1, 1, 2, 1, 2, 3, 2, 1", conveying no
information about list depth.
CSS ([CSS1], [CSS2]) allow users to configure number styles (for all
list, not just ordered) through user style sheets.
Example.
The following CSS 2 style sheet (taken from CSS 2, section 12.5) shows
how to specify compound numbers for nested lists created with either
UL or OL elements. Items are numbered as "1", "1.1", "1.1.1", etc.
End example.
Even without CSS, user agents may allow users to turn on and off
contextual rendering of nested lists.
3.5 Table techniques
Tables were designed to structure relationships among data. In
graphical media, tables are often rendered on a two-dimensional grid,
but this is just one possible interpretation of the data. On the Web,
the HTML TABLE element has been used more often than not to achieve a
formatting effect ("layout tables") rather than as a way to structure
true tabular data ("data tables").
Layout tables cause problems for some screen readers and when
rendered, confuse users. Even data tables can be difficult to
understand for users that browse in essentially one dimension, i.e.
for whom tables are rendered serially. The content of any table cell
that visually wraps onto more than one line can be a problem. If only
one cell has content that wraps, there is less problem if it is in the
last column. Large tables pose particular problems since remembering
cell position and header information becomes more difficult as the
table grows.
User agents facilitate browsing by providing access to specific table
cells and their associated header information. How headers are
associated with table cells is markup language-dependent.
Tabular navigation is required by people with visual disabilities and
some types of learning disabilities to determine the content of a
particular cell and spatial relationships between cells (which may
convey information). If table navigation is not available users with
some types of visual disabilities and learning disabilities may not be
able to understand the purpose of a table or table cell.
3.5.1 Table rendering
A linear view of tables -- cells presented row by row or column by
column -- can be useful, but generally only for simple tables. Where
more complex structures are designed, allowing for the reading of a
whole column from header downward is important as is carrying the
ability to perceive which header belongs to which column or group of
columns if more than one is spanned by that header. It is important
for whole cells to be made available as chunks of data in a logical
form. It might be that a header spans several cells so the header
associated with that cell is part of the document chunk for that and
each of the other cells spanned by that header. Inside the cell, order
is important. It must be possible to understand what the relationships
of the items in a cell are to each other.
Properly constructed data tables generally have distinct TH head cells
and TD data cells. The TD cell content gains implicit identification
from TH cells in the same column and/or row.
For layout tables, a user agent can assist the reader by indicating
that no relationships among cells should be expected. Authors should
not use TH cells just for their formatting purpose in layout tables,
as those TH cells imply that some TD cells should gain meaning from
the TH cell content.
When a table is "read" from the screen, the contents of multiline
cells may become intermingled. For example, consider the following
table:
This is the top left cell This is the top right cell
of the table. of the table.
This is the bottom left This is the bottom right
cell of the table. cell of the table.
If read directly from the screen, this table might be rendered as
"This is the top left cell This is the top right cell", which would be
confusing to the user.
A user agent should provide a means of determining the contents of
cells as discrete from neighboring cells, regardless of the size and
formatting of the cells. This information is made available through
the DOM [DOM1]).
3.5.2 Table rendering as speech
The following techniques for speaking data tables are adapted from the
"Tape Recording Manual" produced by the National Braille Association.
1. Read the title, source, captions and any explanatory keys.
2. Describe the structure of the table. Include the number of
columns, the headings of each column and any associated
sub-columns, reading from left to right. The subhead is not
considered a column. If column heads have footnotes, read them
following each heading.
3. Explain whether the table will be read by rows (horizontally) or
by columns (vertically). The horizontal reading is usual but, in
some cases, the vertical reading better conveys the content. On
rare occasions it is necessary to read a table both ways.
4. Repeat the column headings with the figures under them for the
first two rows. If the table is long, repeat the headings every
fifth row. Always repeat them during the reading of the last row.
5. Indicate the last row by saying, "and finally . . . " or "last row
..."
6. At the completion of the reading say "End table X." If table
appeared on a page other than the one you were recording, add
"Returning to text on page Y."
3.5.3 Cell rendering
Non-graphical rendering of information by a browser or an assistive
technology working through a browser will generally not render more
than a single cell, or a few adjacent cells at a time. Because of
this, the location of a cell of interest within a large table may be
difficult to determine for the users of non-graphical rendering.
In order to provide equivalent access to these users, compliant
browsers should provide a means of determining the row and column
coordinates of the cell having the selection via input (e.g.,
keyboard) commands. Additionally, to allow the user of a non-graphical
rendering technology to return to a cell, the browser should allow a
means of moving the selection to a cell based on its row and column
coordinates.
At the time the user enters a table, or while the selection is located
within a table, the user agent should allow an assistive technology to
provide information to the user regarding the dimensions (in rows and
columns) of the table. This information, in combination with the
summary, title, and caption, can allow the user with a disability to
quickly decide whether to explore the table of skip over it.
Dimensions is an appropriate term, though dimensions needn't be
constants. For example a table description could read: "4 columns for
4 rows with 2 header rows. In those 2 header rows the first two
columns have "colspan=2". The last two columns have a common header
and two subheads. The first column, after the first two rows, contains
the row headers.
Some parts of a table may have 2 dimensions, others three, others
four, etc. Dimensionality higher than 2 are projected onto 2 in a
table presentation.
The contents of a cell in a data table are generally only
comprehensible in context (i.e., with associated header information,
row/column position, neighboring cell information etc.). User agents
provide users with header information and other contextual
information. Techniques for rendering cells include:
* Provide this information through an API.
* Render cells as blocks. This may assist some screen readers. Using
this strategy, the user agent might render individual cells with
the relevant top and side headers attached.
* Allow navigation and querying of cell/header information. When the
selection is on an individual cell, the user would be able to use
a keyboard command to receive the top and left header information
for that cell. The user agent should appropriately account for
headers that span multiple cells.
* Allow users to read one table column or row at a time, which may
help them identify headers.
* Ignore table markup entirely. This may assist some screen readers.
However, for anything more than simple tables, this technique may
lead to confusion.
3.5.4 Cell header algorithm
User agents should use the HTML 4.0 algorithm to calculate header
information ([HTML40], section 11.4.3).
Since not all tables are designed with the header information, user
agents should provide, as an option, a "best guess" of the header
information for a cell. Note that data tables may be organized
top-to-bottom, bottom-to-top, right-to-left, and left-to-right, so
user agents should consider all edge rows when seeking header
information.
Some repair strategies for finding header information include:
* Consider that the top or bottom row to contains header
information.
* Consider that the leftmost or rightmost column in a column group
contains header information.
* If cells in an edge row or column span more than one row or
column, consider the following row or column to contain header
information as well.
The user may choose the form and amount of this information, possibly
announcing the row heads only once and then the column head or its
abbreviation ("abbr") to announce the cell content.
Issues to consider:
1. TH cells on both the left and right of the table need to be
considered.
2. For TH cells with "rowspan" set: the content of those TH cells
must be considered for each of the N-1 rows below the one
containing that TH content.
3. An internal TH in a row surrounded on either side by TDs has no
means to specify to which (row or column) that TH overrides what
existed to its left or above it.
4. Finding column header cells assumes they are all above the TD cell
to which they apply.
5. A TH with "colspan" set needs to be included in the list of TH for
the M-1 columns to the right of the column in which the TH is
found.
If the user agent is taking a guess at header information, the user
agent might find two or more possibilities. Provide the user with a
mechanism to review the possible choices and make a selection.
3.5.5 Table metadata
Users of screen readers or other serial access devices cannot easily
glean information about a page "at a glance". This is particularly
difficult when accessing two-dimensional tables and trying to
determine their content. Therefore, contextual information about
tables (available from author-supplied markup or generated by the user
agent) is very important to making them accessible.
Text metadata about tables can come from a number of elements,
attributes, the structure of the table itself, or other sources.
Useful information to make available to users includes:
* The table caption or summary information.
* The number of column groups and columns.
* The number of row groups and rows, in particular information about
table headers and footers.
* Which rows contain header information (whether at the top or
bottom of the table).
* Which columns contain header information (whether at the left or
right of the table).
* Whether there are subheads.
* How many rows or columns a header spans.
* The row/column dimensions of the table.
The user should be able to get table summary information from inside a
cell. It might be helpful to provide two types of table summary
information, i.e. a brief summary and a more detailed summary.
3.5.6 Table navigation
All users should be able to determine quickly the nature and purpose
of a table. Examining the table visually often conveys a sense of the
table contents with a quick scan of the cells. Users with blindness or
low vision, users who have difficulty translating printed material, or
users in an eyes-busy or speech-based environment may not able to do
this. Table summary information can convey the nature of a table; in
HTML, summary information for tables comes from the "summary"
attribute on the TABLE element as well as the CAPTION element.
An auditory rendering agent, when the point-of-regard moves to a
table, might say, "Table: Tax tables for 1998," thus identifying the
nature of the table. The user could then use keyboard commands to move
the selection to the next logical block of information, or use a
different command to "burrow" into the table.
The "burrow" command should have an opposite "up" command, which would
move the selection from an individual cell to the table as a whole, so
that the user can leave a table from any cell within it, rather than
navigating to the end.
If the user moves the content focus up to look over the summary
information, it should be possible to burrow back to the same cell.
When navigating a table that contains another table, this strategy can
avoid confusion. For example, if each row of a table contained five
cells, but the second row contained a 4x4 table in the third cell, a
user could be disoriented when the row did not end as expected.
However, when the selection moved to the third cell of the table, a
compliant browser would report that this was a table, and describe its
contents. The user would have the option of navigating to the fourth
cell of the parent table, or burrowing into the table within this
cell.
When rendering tabular information, the fact that it is tabular
information should be apparent. For a graphical user agent, such
information is commonly made obvious by the border attribute or by
visually apparent aligned white space between columns. However, for a
non-graphical agent, such information must also be made evident.
As the user agent shifts the selection to a table, it should first
allow users to access summary information about the table (e.g., the
CAPTION element or the "summary" attribute in HTML). Access to this
information allows the user to determine whether or not to examine the
contents of the table, or to move the selection to the next block of
content. Users should be able to choose not to have the summary
information presented, if, for example, they visit a table frequently
and don't want to hear the summary information repeated each time.
In many data tables, the meaning of the contents of a cell are related
to the contents of adjacent cells. For example, in a table of sales
figures, the sales for the current quarter might be best understood in
relation to the sales for the previous quarter, located in the
adjacent cell.
In order to provide access to contextual information for individuals
using non-graphical browsers, or for individuals with certain types of
learning disabilities, it is necessary for the user agent to allow the
selection to be moved from cell to cell, both right/left and up/down
via keyboard commands. The UA should inform the user when navigation
has led to a table edge.
The most direct method of performing such navigation would be via the
cursor keys, though other navigation strategies might be used.
Users of graphical browsers can easily locate cells within a table
that are at the intersection of a row and column of interest. To
provide equivalent access to users of non-graphical browsers,
equivalent means of navigation should be provided. The search function
of a browser will allow the user to locate key terms within a table,
but will not allow the user to find cells that are at the intersection
of rows and columns of interest.
A rich set of navigation functions could include:
* jump to specific cell (by row/column position).
* up/down 1 or more rows
* left/right 1 or more columns
* bottom row in same column
* right column in same row
* jump to row headers for cell
* jump to column headers for cell
* jump back to cell
* go to first or last cell in a row or column.
* relative and direct navigation. For example, entering "-3, 20"
might mean "left three cells, up 20 cells").
* Allow navigation of table headers or footers only.
In some tables, cells may span more than one row or column and this
affects navigation techniques. For example, if you navigate up into a
cell which spans three columns, which cell above the span cell should
you go into if you go up another cell? Or what happens if you are in
the last cell of a row and the previous row has fewer columns?
3.5.7 Table search techniques
* An advanced search mode might provide entries for header
information, allowing the user to find information at the
intersection of columns and rows using the key terms.
* A search mode might allow the user to search for key terms that
are related to key header terms, allowing searches to be
restricted to specific rows or headers within a table.
The header information visible in a TH cell may be abbreviated, in
which case it should be user preference to see the "abbr" value if any
or the full contents.
Axis information may also help the user search into confined portions
of the table.
Column groups and row groups are other confining partitions of a table
in which a search may be limited.
Software:
* Table navigation script from the Trace Center
3.6 Frame techniques
Frames were originally designed for use by graphical user interfaces
to allow the graphical viewport to be broken up into pieces that could
change independently (e.g,. selecting an entry in a table of contents
in one frame changes the contents of a second frame). However Frames
can pose problems users who rely on synthesized speech, refreshable
Braille, and magnified views. The ability to access frame alternatives
is also important for some users with cognitive disabilities. Problems
include:
* Orientation: What frame am I in? How is the frameset organized?
What is the relationship among frames? What happens in frame B
when I select a link in frame A?
* Navigation: How do I get from frame to frame?
To help users, user agents should:
* Consider the author's alternative presentation to frames (e.g.,
provided by the HTML 4.0 NOFRAMES element ([HTML40], section
16.4.1).
* Inform the user that they are viewing a frameset.
* Provide information about the number of frames in the frameset.
* Provide (possibly nested) lists of links to each frame in the
frameset. The link text can be the frame title (given by "title"
or "name" if "title" is not present). Or, if no title or name are
available, render the title (e.g., the HTML TITLE element
[HTML40], section 7.4.2) of the document that is loaded into the
frame. Other alternative renderings for a frameset include simply
rendering each frame in the frameset sequentially as a block
(e.g., aligned vertically in a graphical environment).
* Highlight the current frameset (e.g., with a thick border, by
displaying the name of the current frameset in the status bar,
etc.
* Provide information about the current frame. Make available frame
title for speech synthesizers and Braille displays.
* If a page does not have a list of links within a frame available
outside the frame, make the list available outside the frame.
* Allow navigation between frames (forward and backward through the
nested structure, return to global list of links to frames). Note.
Recall that the user must be able to navigate frames through all
supported input devices.
* Allow navigation to equivalent alternatives.
* Allow the user to bookmark the current frame.
* Inform the user if an action in one frame causes the content of
another frame to change. Allow the user to navigate quickly to the
frame(s) that changed.
To name frames in HTML, use:
1. The "title" attribute on FRAME, or if not present,
2. The "name" attribute on FRAME, or if not present,
3. Title information of the referenced frame source (e.g., the TITLE
element of the source HTML document), or
4. Title information of the referenced long description (e.g., what
"longdesc" refers to in HTML), or
5. Frame context (e.g., "Frame 2.1.3" to indicate the path to this
frame in nested framesets).
Users may also use information about the number of images and words in
the frame to guess the purpose of the frame. For example, few images
and few words is probably a title, more words is probably an index,
many words is probably text area.
Frame structure information should be available through the DOM and
appropriate accessibility interfaces. Using DOM and operating specific
accessibility API to expose frame information provides one means for
assistive technologies to provide alternative control of frames and
rendering of frame information. The user agent should fully implement
the DOM Level 1 Recommendation [DOM1] API related to frames:
HTMLFrameSetElement, HTMLFrameElement, and HTMLIFrameElement.
For people with visual disabilities who enlarge text on the screen to
improve readability, frames become distorted and unusable. Other users
with cognitive disabilities sometimes become disoriented in complex
side-by-side frame configurations. To improve access to frames, user
agents should allow frames to be viewed as a list so the user can
identify the number of frames and the functions of each frame. If
NOFRAMES information is present it should also be rendered so the user
can optionally use that view of the information.
Consider renderings of the following document:
Time Value of Money
The following illustrate how some user agents handle this frameset.
First, rendering in Microsoft Internet Explorer 5.0 on a Windows
platform:
Image shows the example frameset with five frame panes rendered in
Microsoft Internet Explorer 5.0
Rendering by Lynx on Linux:
Time Value of Money
FRAME: Size buttons
FRAME: Presentation Outline
FRAME: Navigation buttons
FRAME: Slide Image
FRAME: Notes
List of Presentation Slides
1. Time Value of Money
2. Topic Overview
3. Terms and Short Hand
4. Future Value of a Single CF
5. Example 1: FV example:The NBA's new Larry Bird exception
6. FV Example: NBA's Larry Bird Exception (cont.)
7. SuperStar's Contract Breakdown
8. Present Value of a Single Cash Flow
9. Example 2: Paying Jr, and A-Rod
10. Example 3: Finding Rate of Return or Interest Rate
11. Annuities
12. FV of Annuities
13. PV of Annuities
14. Example 4: Invest Early in an IRA
15. Example 4 Solution
16. Example 5: Lotto Fever
17. Uneven Cash Flows: Example 6:Fun with the CF function
18. Example 6 CF worksheet inputs
19. CF inputs continued
20. Non-Annual Interest Compounding
21. Example 7: What rate are you really paying?
22. Nominal to EAR Calculator
23. Continuous Interest Compounding
24. FV and PV with non-annual interest compounding
25. Non-annual annuities
26. Example 8: Finding Monthly Mortgage Payment
27. solution to Example 8
Graphical rendering by Home Page Reader on Windows:
Image shows the example frameset with five links for each of the frame
elements in IBM home page reader
Audio rendering by Home Page Reader on Windows: @@add here?@@
User agents may also indicate the number of frames in a document and
which frame is the current frame via the menu bar or popup menus.
Users can configure the user agent to include a FRAMES menu item in
their menu bar. The menu bar makes the information highly visible to
all users and is very accessible to assistive technologies. In the
following snapshot, the menu bar indicates the number of frames and a
check next to the name of the frame element indicates which is the
current frame:
Image shows a pull down menu indicating the number of frames in a
document, the labels associated with each frame, and a check mark to
indicate the current frame
3.7 Form techniques
For labels explicitly associated with form controls (e.g., "for"
attribute on LABEL in HTML), make available label information when the
user is navigating among the form controls. This information must be
provided in a device-independent manner, and the user should be able
to choose from a list of mechanisms that provide access to the content
of the label.
For semantic information explicitly associated with groupings of form
controls (e.g., groupings of radio buttons or checkboxes contained in
a FIELDSET), make available the information contained in the LEGEND
defined for the FIELDSET to the user. This information must be
provided in a device-independent manner, and the user should be able
to choose from a list of mechanisms that provide access to the content
of the LEGEND.
Provide information about the percentage of form that has already been
filled out as the user moves through the form controls. This
information must be provided in a device-independent manner. The user
should also be able to query the user agent through a simple,
well-documented mechanism (such as a keystroke or keystroke
combination) to learn what percentage of the form has been completed.
Allow the user to know what percentage of a form has been completed as
the user navigates the form. will help users avoid prematurely
submitting an incomplete form. This is particularly important for
anyone moving through a form sequentially; users who encounter a
submit button usually think this means the end of a form, but it may
not be. (Refer also to the technique detailing methods of providing
users with orientation information about individual form controls when
a form control receives content focus for a more detailed discussion
of this issue.)
Provide the user with orientation information about a form. Users
should be able to query the user agent for:
* the presence of a form -- the user should be able to query to user
agent for the presence of a form within the document being
rendered. Some user agents (such as Opera and Netscape Navigator)
already indirectly provide such functionality in a non-interactive
manner, through the provision of "form navigation" keyboard
commands. When invoked, these "form navigation" commands move the
user agent's current focus to the first form field contained in
the document currently being rendered (provided, of course, that
the document contains a form. Although providing discrete "form
navigation" commands allows users to quickly move to the first
form field within a document, users need to be explicitly notified
if the document does not contain a form. Such notification should
be conveyed in a device-independent manner, and the user should
not be limited to one means of notification (i.e., display a
message on the status bar and play a sound).
* the number of forms in a document
Provide the user with orientation information about individual form
controls when a form control receives content focus. For example, the
most basic orientation information would be to identify the form
control with focus as "Field X of Y", where "Y" is the total number of
fields contained in the form. This will help prevent users accessing
the form serially (such as a blind user using a screen reader or
someone using a voice browser over a phone) from prematurely invoking
the form's submit mechanism. It is a common practice for forms
(particularly those used to query search engines) to be laid out
visually, so that the submit and reset buttons (if present)
immediately follow a text-entry field, despite the presence of other
form controls (such as radio buttons and checkboxes) within the FORM
element. A user accessing such a form in a serial manner, therefore,
is likely to mistake the submit button for the end of the form, and
activate it, unaware that it is followed by further form controls
which could -- in the example of a search engine query submission form
-- prove an invaluable aid in tailoring the content being submitted
via the form. Use of such orientation information (i.e., "Field X of
Y" or the percentage of the form completed) will also decrease the
amount of time needed to submit the form (a crucial consideration when
forms are being used to facilitate bidding for online auctions) as
well as reduce the frustration of the end user, who, due to the
visually oriented layout of the form, is confused when the submission
of the form repeatedly leads to a message such as "Form Incomplete -
Use your browser's back button to return to the form".
When a document contains more than one form, form control orientation
information should also include data which will identify to which form
the form control with focus belongs. Notification could take the form:
Form Z: Field X of Y
where "Z" identifies the form, "X" the form field with focus an "Y"
the total number of form fields contained in "Form Z".
Provide more detailed orientation information pertaining to form:
* When a grouping of radio buttons receives content focus, identify
the radio button with content focus as "Radio Button X of Y",
where "Y" represents the total number of radio buttons in the
grouping. HTML 4.0 HTML 4.0 specifies the FIELDSET element
([HTML40], section 17.10), which allows authors to group
thematically related controls and labels. The LEGEND element
([HTML40], section 17.10) assigns a caption to a FIELDSET. If a
LEGEND has been defined for the grouping of radio boxes, use the
information contained within the LEGEND to more precisely identify
the number of radio buttons in the grouping. For example, if the
LEGEND element has been used to identify a FIELDSET of radio
buttons, each of which has a LABEL element ([HTML40], section
17.9.1) associated with it, as "Connection Rate", identify the
radio button as it receives content focus as "Connection Rate:
Radio button X of Y: 28.8kpbs", where "Y" represents the total
number of radio buttons in the grouping and "28.8kbps" is the
information contained in the LABEL associated with the radio
button with content focus.
* Provide information about what is required for each form control.
GUI browsers, for example, could convey such information via
context-sensitive help. Lynx conveys this information by providing
information about the currently selected form control via a status
line message:
+ (Radio Button) Use right-arrow or RETURN to toggle
+ (Checkbox Field) Use right-arrow or RETURN to toggle
+ (Option List) Hit return and use arrow keys and return to
select option
+ (Text Entry Field) Enter Text. Use UP or DOWN arrows or "tab"
to move off
+ (Textarea) Enter text. UP/DOWN arrows or "tab" to move off
(^Ve for editor) Note. The ^Ve (caret-V, e) command, included
in the TEXTAREA status line message, enables the user to
invoke an external editor defined in the local Lynx
configuration file (lynx.cfg). For more information, please
refer to the following technique.
Allow the user to invoke an external editor when a TEXTAREA receives
content focus. A user may wish to use an external editor, rather than
enter text directly in a TEXTAREA for myriad reasons, including:
* the ability to more efficiently and expeditiously review the text
being input
* the ability to spell check the text being input
* the ability to use macros or other special features of the
external editor, including the ability to increase the contrast
between foreground and background colors, access to a wider range
of screen-display fonts, etc.
* the ability to save a local copy of the text being input
* the user's familiarity with the external editor will encourage the
user to actually enter text into a TEXTAREA--an exercise which is
often an extremely daunting task, given the limitations imposed by
the physical dimensions of the TEXTAREA. A user will also find it
much easier to review what he or she has typed when using an
external editor.
Provide information about the order of form controls (e.g., as
specified by "tabindex" in HTML). This is important since:
* most forms are visually oriented, employing changes in font size
and color
* users who access forms serially need to know they have supplied
all the necessary information before submitting the form.
Provide information about required fields. Since authors often use
color changes, font styling, or a graphical symbol alone to express
that a field is required, the user should be able to configure the
user agent so that it alerts him that the field is required for
submission of the form content. Strategies for achieving this include:
* Allow the user to view a list of required form fields. Such a list
should be invokable via a simple and well documented keybinding.
* Allow the user to define an alert mechanism (such as the playing
of a sound) which will be invoked when a required field receives
content focus. The user should be able to pick from amongst a
list of alert mechanisms (i.e. color or font-style changes to the
field label, the playing of a sound clip, a status line message,
etc.), and should not be limited to only one type of alert
mechanism. Do not rely on visual or aural prompts alone to signify
a required form field.
Allow the user to configure the user agent so that SELECT form fields
which use the "multiple" attribute to allow the end user to select
more than one OPTION can be transformed into a list of checkboxes.
* Preserve the LABELs set for the OPTGROUP and each individual
OPTION, and re-associate them with the user agent generated
checkboxes. The LABEL defined for the OPTGROUP should be converted
into a LEGEND for the resultant FIELDSET, and each checkbox should
retain the LABEL defined for the corresponding OPTION.
* Note. Lynx automatically transforms SELECT form fields which use
the "multiple" attribute to allow the end user to select more than
one OPTION into checkboxes.
Allow the user to exit a menu without selecting any option. For
example, when navigating through OPTION's, have some key like the ESC
key ot exit the list of OPTION's without making a selection.
Allow the user to configure the user agent sot that SELECT form fields
can be transformed into a list of radio buttons.
* Any such transformation should retain the accessibility
information defined for the original form controls.
* Note. Lynx provides this functionality as a configurable option,
which can be changed on-the-fly while a page is being rendered. To
promote the comprehensibility of the transformed output for users
using screen-readers and refreshable Braille displays, Lynx places
each OPTION that it transforms into a radio button on a separate
line.
3.7.1 Form submission techniques
Users (notably users with blindness or any user unaccustomed to online
forms) do not want forms to be submitted without their consent, e.g.,
when submitted through scripts. In this case user agents should
request confirmation before submitting the form content. Nor do they
wish to be prompted before each form submission when they have
explicitly submitted the form (e.g., through the standard submit
button).
Inadvertently pressing the RETURN or ENTER key is quite a prevalent
phenomenon among users of every level of expertise - especially those
who often find it necessary to switch between user agents. Lynx, for
example, uses the ENTER key within FORMs as a means of exposing
drop-down (or pop-up, depending upon your point of view) SELECT menus.
Thus, when one encounters a SELECT menu using Lynx, one: exposes the
content of the menu by pressing the ENTER key, and then is able to
navigate between OPTIONs using the up and down arrows or via Lynx's
text-search feature. When one finds the appropriate OPTION, it is
selected by pressing ENTER, which causes the selected item to be
displayed in the SELECT menu listbox.
The problem posed by the default "submit on enter" feature of most GUI
browsers is not limited to the SELECT menu problem outlined above.
Lynx (as well as several other text-based browsers) uses the
ENTER/RETURN key as a means of toggling several FORM controls, such as
the selection of checkboxes and radio buttons.
Speech users may be frustrated and misdirected by the use of
javascript and event handler controlled pseudo-forms, wherein the user
is presented with a menu (in the form of a listbox in GUI browsers),
and is redirected to a different viewport upon selection of an OPTION.
The markup behind such pseudo-forms is a mix of javascript (in
particular the "function switchpage(select)" command) and HTML FORM
controls, which utilize HTML4's event handler script attributes (in
particular the "onchange" event handler attribute has been defined. An
example (gleaned from the document source for one Web site follows: