Techniques:
Provide a preview
mode that displays alternative content. Although this may quickly give
authors a clear understanding of some problems, they should be warned
that there are many other less predictable ways in which a page may be
presented (aurally, text-only, text with pictures separately, on a small
screen, on a large screen, etc.). Other helpful document views include: a
"no style sheets" view and a "no images" view.
Prompt the
author to provide equivalent alternative information (e.g., captions,
auditory descriptions, and collated text transcripts for video). Because
this ATAG checkpoint has a relative priority, it is the priority of the
relevant WCAG checkpoints that determines the level of conformance of the
tool to the ATAG checkpoint :
- WCAG
1.1(P1)
Provide text equivalent for non-text elements.
- Short
Text Labels (for alternate text, titles, etc.): These
types of alternative equivalents require only short text strings
from the author, so the prompts for them may be best located as
text boxes within property dialogs, etc. An important
consideration is that the function of the object (decorative,
button, spacer, etc.) will be important to the instructions given
to the author on what to write. The object function may be
prompted for or discovered by automated heuristics.
- Long
Descriptions:These types of alternative equivalents
require more screen area to author and are only required when the
object is not already sufficiently described. The author may
first be prompted as to whether the inserted object is adequately
described (a "no images" view may help them decide). If the short
description is inadequate, the author should be prompted for the
location of a preexisting description. Failing that, the author
will need a description writing utility (that would include a
preview of the object and description writing pointers). Since
description writing can be time-consuming, it is preferable for
the tool to have some ability to store and reuse the description
(see ATAG10
3.5) as an incentive for the author.
- Transcripts of Audio or Video: The author
should be prompted for the location of a preexisting transcript
of the audio or video. Failing this, one will have to be created.
Although transcript writing is a complex process for long media
files, tools might include simple transcription writing suites
(with built-in media players) for short media files.
- Captions for Video:The author should be
prompted for the location of a captioned version of the video.
The creation of captions can be a time consuming process but
public domain tools do exist for relatively simple captions
(e.g., Magpie).
- Signed Translation of Audio or Video: The
author should be prompted for the location of a version of the
audio or video with signed translation. The creation of signed
translation video files is assumed to be beyond the average
author but new technologies are being developed for automated
sign language animation to be generated from text.
- Still Images of Video: The author should be
prompted for the location of a still image. If this fails, the
tool might allow the user to take a snapshot from the video to
use as the still.
- Ideogram Rubies (for Japanese, Chinese, and other
appropriate languages): When unusual ideograms are
inserted, prompt the author for text that can be used as a ruby. This
can be done in the same way as short
text labels.
- WCAG
1.2 (P1) Provide redundant text links for server-side image
map areas.
- Image map
labels: Image maps require multiple text labels (one for
each area) as well as redundant text links. Since the same labels
may be used for the area labels and the text links, the tool
might prompt the author to add all the labels and text links for
all the areas at the same time (rather than a separate prompt for
each area). To aid the author, the tool might search the document
for links that point to the same URI, then use the link text as
place-holder text in the labeling prompt.
- WCAG
1.3 (P1) Provide auditory descriptions for multimedia.
- Audio Descriptions of Video: The author should
be prompted for the location of a described version of the video.
The recording of traditional video descriptions (that are encoded
into the video file where silent periods occur in the original
soundtrack) is a complex process that may be beyond the average
author. However, technologies are becoming available that allow
the audio description files to be stored separately, to be played
only if requested by the user.
- WCAG
1.5 (P3) Provide redundant text links for client-side image
map areas.
- WCAG
5.3 (P2) Avoid layout tables or provide an alternative
equivalent.
- Alternative
Information:The author should be prompted for the
location of the alternative content. If there is no alternative
content, the tool might support the author by providing a copy of
the content with the problematic formatting removed.
- Element Role: The roles that elements play
(e.g., tables for layout or data; frames for navigation bars,
headers, etc.) are important for a number of WCAG10 checkpoints.
To determine the role of a particular element instance, the tool
might query the author. The answer received should be saved by
some means to prevent having to ask the question again.
Alternatively, some tools might use automated heuristics to
determine which role the table is playing.
- WCAG
5.5 (P3) Provide summaries for tables.
- WCAG
6.2 (P1) Keep equivalents for dynamic content up to
date.
- Keeping equivalents up to date: When base
content, associated with alternative equivalent information,
changes, prompt the author to ensure that equivalent still covers
the functionality of the base content.
- WCAG
6.3 (P1) Ensure pages usable without scripts, applets,
programmatic objects. Else, provide equivalent information.
- WCAG
6.5 (P2) Ensure dynamic content is accessible or provide an
alternative presentation.
- WCAG
10.4 (P3) Include place-holding text in edit boxes and text
areas.
- Form field place-holders: When tools prompt
the author for this text, they might suggest nearby text strings
(which may be implicit labels).
- WCAG
12.1 (P1) Title each generated frame.
- WCAG
12.2 (P2) Describe the purpose and relation of frames.
- WCAG
13.1(P2)
Clearly identify the target of each link.
- WCAG
13.3 (P2) Provide information about the general layout of a
site.
- Site information: Tools might prompt the
author to provide a link or content describing the structure of
the site, and its accessibility features as part of a list of
general considerations displayed after an accessibility check,
etc.
- WCAG
13.9 (P3) Provide information about document collections
(i.e., documents comprising multiple pages.).
- Document Collections Information: Tools might
ask authors to specify the role of pages linked from a navigation
bar. Where common names are used (search, home, map) as links,
tools might ask the author to confirm these functions for use in
linking.
- WCAG
14.2 (P3) Supplement text with graphic or auditory
presentations.
- Multimedia Supplements: Since prompting the
author about every instance of text is intolerable, this
requirement might be included in a list of general considerations
displayed after an accessibility check, etc.
- The following WCAG10
checkpoints are not considered relevant to this checkpoint (since they do
not refer to instances of equivalent alternatives):
- WCAG 2.1 (P1) Ensure information provided with
color is also available without color.
- WCAG 2.2 (Images: P2, Text: P3) Use sufficient
foreground/background contrast.
- WCAG 3.1 (P2) Use markup rather than images to
convey information.
- WCAG 3.2 (P2) Validate to published formal
grammars.
- WCAG 3.3 (P2) Use style sheets.
- WCAG 3.4 (P2) Use relative units.
- WCAG 3.5 (P2) Use header elements.
- WCAG 3.6 (P2) Use lists and list items
properly.
- WCAG 3.7 (P2) Use quotations properly.
- WCAG 4.1 (P1) Identify natural language
changes.
- WCAG 4.2 (P3) Specify abbreviation or acronym
expansions.
- WCAG 4.3 (P3) Identify the primary natural
language of documents.
- WCAG 5.1 (P1) Identify data table row and column
headers.
- WCAG 5.2 (P1) Associate data cells and header
cells in complex data tables.
- WCAG 5.4 (P2) Avoid structural markup in layout
tables.
- WCAG 5.6 (P3) Provide abbreviations for table
header labels.
- WCAG 6.1 (P1) Organize documents to be read
without style sheets.
- WCAG 6.4 (P2) Ensure script and applet event
handlers are input device-independent.
- WCAG 7.1 (P1) Avoid causing screen to flicker.
- WCAG 7.2 (P2) Avoid causing content to blink.
- WCAG 7.3 (P2) Avoid causing movement on the
screen.
- WCAG 7.4 (P2) Avoid periodically auto-refreshing
pages.
- WCAG 7.5 (P2) Avoid redirecting pages
automatically. Use server redirects.
- WCAG 8.1 (Important: P1, Else: P2) Make
programmatic elements (scripts, applets) directly accessible or AT
compatible.
- WCAG 9.1 (P1) Use client-side image maps instead
of server-side image maps.
- WCAG 9.2 (P2) Ensure element with own interface
are input device-independent.
- WCAG 9.3 (P2) Specify logical (device independent)
event handlers for scripts.
- WCAG 9.4 (P3) Create a logical tab order.
- WCAG 9.5 (P3) Provide keyboard shortcuts to
important elements.
- WCAG 10.1 (P2) Avoid spawned windows.
- WCAG 10.2 (P2) Implicitly associate labels with
form controls.
- WCAG 10.3 (P3) Provide a linear text alternative
to tables with text in parallel, word-wrapped columns.
- WCAG 10.5 (P3) Include non-link characters between
adjacent links.
- WCAG 11.1 (P2) Use W3C technologies.
- WCAG 11.2 (P2) Avoid deprecated features of W3C
technologies.
- WCAG 11.3 (P3) Include metadata information (e.g.,
language, content type, etc.)
- WCAG 11.4 (P1) Keep alternative pages synchronized
with original pages.
- WCAG 12.3 (P2) Divide large blocks of information
into manageable groups.
- WCAG 12.4 (P2) Associate labels explicitly with
their controls.
- WCAG 13.2 (P2) Provide metadata to pages and
sites.
- WCAG 13.4 (P2) Provide navigation mechanisms in a
consistent manner.
- WCAG 13.5 (P3) Provide navigation bars.
- WCAG 13.6 (P3) Group, identify, and provide a way
to bypass related links.
- WCAG 13.7 (P3) Enable different types of
searches.
- WCAG 13.8 (P3) Provide distinguishing information
at the beginning of headings, paragraphs, lists, etc.
- WCAG 13.10 (P3) Provide a means to skip over
multi-line ASCII art.
- WCAG 14.1 (P1) Use clearest and simplest language
appropriate.
- WCAG 14.3 (P3) Use a consistent style of
presentation
Reference:
- For more information on different methods for prompting, see Appendix A.
ATAG
Checkpoint 3.2: Help the author create structured content and separate
information from its presentation. [Relative Priority]
Techniques:
Help the
author create structured content and separate information from its
presentation as required by the following WCAG10 checkpoints. (Note: An
asterix (*) denotes those WCAG checkpoints that involve the inclusion of
equivalent alternative information which, although related to the
separation of information from presentation, is already covered by ATAG
3.1) :
- WCAG
2.1(P1)
Ensure information provided with color is also available without
color.
- Prompt the author to ensure a color independent indicator.
- WCAG
2.2 (Images: P2, Text: P3) Use sufficient
foreground/background contrast.
- Provide a monochrome preview for the author to test themselves.
- When a foreground or background color is defined, prompt for a
contrasting background or foreground color.
- WCAG
3.1 (P2) Use markup rather than images to convey
information.
- WCAG
3.2 (P2) Validate to published formal grammars.
- WCAG
3.3 (P2) Use style sheets.
- Prompt the author to identify the structural role of content
that has been emphasized through styling.
- Provide a view which allows the author to edit the layout and
styling effects independently of the text content.
- Recognize formatting patterns and convert them to style rules.
- WCAG
3.4 (P2) Use relative units.
- WCAG
3.5 (P2) Use header elements.
- Prompt the author to identify headings and subheadings.
- Provide an "outline" or "structure" view which allows the
author to easily grasp the heading structure, and edit it.
- WCAG
3.6 (P2) Use lists and list items properly.
- Recognize formatting conventions such as a number of
consecutive paragraphs beginning with a bullet character (this
may be a "bullet" or another punctuation character like asterisk
or dash "-") being used to identify a list.
- Include lists (marked as lists) in a collapsible structure
view.
- WCAG
3.7 (P2) Use quotations properly.
- Where material appears within quote marks ask the author if
this is a quotation.
- WCAG
4.1 (P1) Identify natural language changes.
- Use a dictionary lookup system to recognize changes of
language, or use of abbreviations and acronym.
- WCAG
4.2 (P3) Specify abbreviation or acronym expansions.
- Recognize collections of uppercase letters as likely
abbreviations (in languages that have case) and prompt the author
for an expansion, to be provided in markup (e.g., in HTML, with
abbr
or acronym
).
- WCAG
4.3 (P3) Identify the primary natural language of
documents.
- Prompt the author (and allow them to specify a default
suggestion) for the language of a document.
- WCAG
5.1 (P1) Identify data table row and column headers.
- Prompt the author to provide header information for tabular
data.
- WCAG
5.2 (P1) Associate data cells and header cells in complex
data tables.
- Ask the author to group columns, rows, or blocks of cells that
are related.
- WCAG
5.3 (P2) Avoid layout tables or provide an alternative
equivalent.
- Prompt the author to identify tables as used for layout or
data.
- For layout tables, provide a linearized version, and offer it
as a link from the table or as a replacement.
- Incorporate tablin, a
tool that linearizes and transforms tables.
- WCAG
5.4 (P2) Avoid structural markup in layout tables.
- WCAG
5.6 (P3) Provide abbreviations for table header
labels.
- WCAG
6.1 (P1) Organize documents to be read without style
sheets.
- Provide a "draft" view which does not apply styling.
- WCAG
6.3 (P1) Ensure pages usable without scripts, applets,
programmatic objects. Else, provide equivalent information*.
- Prompt for alternative content for applets and programmatic
objects.
- Prompt for server-side alternatives for essential client-side
scripts (those used for content and navigation) and applets.
- WCAG
6.4 (P2) Ensure script and applet event handlers are input
device-independent.
- During applet development, prompt the author to include
device-independent means of activation.
- Include a "no scripts" view.
- WCAG
6.5 (P2) Ensure dynamic content is accessible or provide an
alternative presentation*.
- WCAG
7.1 (P1) Avoid causing screen to flicker.
- WCAG
7.2 (P2) Avoid causing content to blink.
- WCAG
7.3 (P2) Avoid causing movement on the screen.
- WCAG
7.4 (P2) Avoid periodically auto-refreshing pages.
- WCAG
7.5 (P2) Avoid redirecting pages automatically. Use server
redirects.
- WCAG
9.1 (P1) Use client-side image maps instead of server-side
image maps.
- Where regions are not easily defined, ask the author to provide
information that can be used to generate a form-based input
method and explains how the coordinates input will be used. For
example, for a geographic map the input might be used to look up
latitude and longitude of a point and then give information about
that point.
- WCAG
9.2 (P2) Ensure element with own interface are input
device-independent.
- WCAG
9.3 (P2) Specify logical (device independent) event handlers
for scripts.
- WCAG
9.4(P3)
Create a logical tab order.
- Provide a link to skip over objects (since some browsers cause
objects to permanently capture the tab focus).
- Where there are only a few links that change in each page of a
collection, ask the author if they should receive focus first. If
so, then appropriately update the tabindex order.
- WCAG
9.5 (P3) Provide keyboard shortcuts to important
elements.
- Ask authors to specify an accesskey for links that appear
common to a number of pages.
- WCAG
10.1 (P2) Avoid spawned windows.
- WCAG
10.3 (P3) Provide a linear text alternative to tables with
text in parallel, word-wrapped columns.
- WCAG
11.2 (P2) Avoid deprecated features of W3C
technologies.
- WCAG
11.3 (P3) Include metadata information (e.g., language,
content type, etc.)
- WCAG
12.2 (P2) Describe* the purpose and relation of frames.
- Prompt the author for a longdesc for each frame in a frameset.
- Prompt the author to add a noframes section to the frameset.
Encourage the author to include sufficient links to navigate the
site, and relevant information. For example, where a frameset
defines a navigation frame and a welcome page, include the
content of each of these frames in the noframes.
- When frames used for a mosaic of images, allow inclusion of
markup files (with images embedded) rather than images directly.
- WCAG
12.3 (P2) Divide large blocks of information into manageable
groups.
- Where there are more than 10 choices in a list
(
select
, checkbox
or radio
boxes) ask the author to identify subgroups.
- WCAG
12.4 (P2) Associate labels explicitly with their
controls.
- Ask authors to mark explicitly the labels for form inputs
(
input
and textarea
elements).
- WCAG
13.2 (P2) Provide metadata to pages and sites.
- Metadata: Ask authors for information about a
page or site. If its function is known (see also WCAG checkpoint
13.9) add this information as metadata.
- WCAG
13.6 (P3) Group, identify, and provide a way to bypass
related links.
- Ask authors if lists of links are a group and should be a map.
- WCAG
14.1 (P1) Use clearest and simplest language
appropriate.
- Provide readability ratings for text.
- Provide a thesaurus function.
- Provide a grammar-checking function.
- The following WCAG10
checkpoints are not considered relevant to this checkpoint (since they do
not refer to the creation of structured content or the separation of
information from its presentation):
- WCAG 1.1 (P1) Provide text equivalent* for
non-text elements.
- WCAG 1.2 (P1) Provide redundant text links* for
server-side image map areas.
- WCAG 1.3 (P1) Provide auditory descriptions* for
multimedia.
- WCAG 1.4 (P1) Provide synchronized equivalent
alternatives* for time-based multimedia.
- WCAG 1.5 (P3) Provide redundant text links* for
client-side image map areas.
- WCAG 5.5 (P3) Provide summaries* for tables.
- WCAG 6.2 (P1) Keep equivalents* for dynamic
content up to date.
- WCAG 8.1 (Important: P1, Else: P2) Make
programmatic elements (scripts, applets) directly accessible or AT
compatible.
- WCAG 10.2 (P2) Implicitly associate labels with
form controls.
- WCAG 10.4 (P3) Include place-holding text* in edit
boxes and text areas.
- WCAG 10.5 (P3) Include non-link characters between
adjacent links.
- WCAG 11.1 (P2) Use W3C technologies.
- WCAG 11.1 (P2) Use W3C technologies.
- WCAG 11.4 (P1) Keep alternative pages synchronized
with original pages.
- WCAG 12.1 (P1) Title* each generated frame.
- WCAG 13.1 (P2) Clearly identify the target* of
each link.
- WCAG 13.3 (P2) Provide information* about the
general layout of a site.
- WCAG 13.4 (P2) Provide navigation mechanisms in a
consistent manner.
- WCAG 13.5 (P3) Provide navigation bars.
- WCAG 13.7 (P3) Enable different types of
searches.
- WCAG 13.8 (P3) Provide distinguishing information
at the beginning of headings, paragraphs, lists, etc.
- WCAG 13.9 (P3) Provide information* about document
collections (i.e., documents comprising multiple pages.).
- WCAG 13.10 (P3) Provide a means to skip over
multi-line ASCII art.
- WCAG 14.2 (P3) Supplement text with graphic or
auditory presentations*.
- WCAG 14.3 (P3) Use a consistent style of
presentation.
Reference:
- The WAI Evaluation and Repair group [WAI-ER] is developing a
document that discusses detailed techniques for testing the accessibility
of content according to the Web Content Accessibility Guidelines, and
methods of repairing it. A draft of that document is available [AUTO-TOOL].
- Provide an outline view that lets the author clearly see the structure
of the document independently of the specified presentation
- Support author's of DTD's or Schemas to specify explicit structure. For
example, encourage nesting where appropriate.
Sample(s):
ATAG Checkpoint
3.3: Ensure that prepackaged content conforms to the Web Content
Accessibility Guidelines 1.0 [WCAG10]. [Relative Priority]
Note:Prepackaged content refers to images, multimedia,
applets, scripts, etc. Markup content is considered under templates (ATAG checkpoint 1.4).
Including pre-written descriptions for all multimedia files (e.g., clip-art)
packaged with the tool will save authors time and effort, cause a significant
number of professionally written descriptions to circulate on the Web,
provide authors with convenient models to emulate when they write their own
descriptions, and show authors the importance of description writing.
Techniques:
Provide
prepackaged content in formats that allow for accessible annotation to be
included in the files, such as SMIL, PNG, and SVG.
- Ensure that prepackaged content conforms to the following WCAG10 checkpoints.
- The following WCAG10
checkpoints are not considered relevant to this checkpoint:
- WCAG 1.2 (P1) Provide redundant text links for
server-side image map areas.
- WCAG 1.5 (P3) Provide redundant text links for
client-side image map areas.
- WCAG 3.1 (P2) Use markup rather than images to
convey information.
- WCAG 3.2 (P2) Validate to published formal
grammars.
- WCAG 3.3 (P2) Use style sheets.
- WCAG 3.4 (P2) Use relative units.
- WCAG 3.5 (P2) Use header elements.
- WCAG 3.6 (P2) Use lists and list items
properly.
- WCAG 3.7 (P2) Use quotations properly.
- WCAG 4.1 (P1) Identify natural language
changes.
- WCAG 4.2 (P3) Specify abbreviation or acronym
expansions.
- WCAG 4.3 (P3) Identify the primary natural
language of documents.
- WCAG 5.1 (P1) Identify data table row and column
headers.
- WCAG 5.2 (P1) Associate data cells and header
cells in complex data tables.
- WCAG 5.3 (P2) Avoid layout tables or provide an
alternative equivalent.
- WCAG 5.4 (P2) Avoid structural markup in layout
tables.
- WCAG 5.5 (P3) Provide summaries for tables.
- WCAG 5.6 (P3) Provide abbreviations for table
header labels.
- WCAG 6.1 (P1) Organize documents to be read
without style sheets.
- WCAG 6.2 (P1) Keep equivalents for dynamic content
up to date.
- WCAG 6.3 (P1) Ensure pages usable without scripts,
applets, programmatic objects. Else, provide equivalent
information.
- WCAG 7.4 (P2) Avoid periodically auto-refreshing
pages.
- WCAG 7.5 (P2) Avoid redirecting pages
automatically. Use server redirects.
- WCAG 9.1 (P1) Use client-side image maps instead
of server-side image maps.
- WCAG 9.4 (P3) Create a logical tab order.
- WCAG 9.5 (P3) Provide keyboard shortcuts to
important elements.
- WCAG 10.1 (P2) Avoid spawned windows.
- WCAG 10.2 (P2) Implicitly associate labels with
form controls.
- WCAG 10.3 (P3) Provide a linear text alternative
to tables with text in parallel, word-wrapped columns.
- WCAG 10.4 (P3) Include place-holding text in edit
boxes and text areas.
- WCAG 10.5 (P3) Include non-link characters between
adjacent links.
- WCAG 11.2 (P2) Avoid deprecated features of W3C
technologies.
- WCAG 11.4 (P1) Keep alternative pages synchronized
with original pages.
- WCAG 12.1 (P1) Title each generated frame.
- WCAG 12.2 (P2) Describe the purpose and relation
of frames.
- WCAG 12.3 (P2) Divide large blocks of information
into manageable groups.
- WCAG 12.4 (P2) Associate labels explicitly with
their controls.
- WCAG 13.1 (P2) Clearly identify the target of each
link.
- WCAG 13.2 (P2) Provide metadata to pages and
sites.
- WCAG 13.3 (P2) Provide information about the
general layout of a site.
- WCAG 13.4 (P2) Provide navigation mechanisms in a
consistent manner.
- WCAG 13.5 (P3) Provide navigation bars.
- WCAG 13.6 (P3) Group, identify, and provide a way
to bypass related links.
- WCAG 13.7 (P3) Enable different types of
searches.
- WCAG 13.8 (P3) Provide distinguishing information
at the beginning of headings, paragraphs, lists, etc.
- WCAG 13.9 (P3) Provide information about document
collections (i.e., documents comprising multiple pages.).
- WCAG 13.10 (P3) Provide a means to skip over
multi-line ASCII art.
- WCAG 14.1 (P1) Use clearest and simplest language
appropriate.
- WCAG 14.2 (P3) Supplement text with graphic or
auditory presentations.
- WCAG 14.3 (P3) Use a consistent style of
presentation.
ATAGCheckpoint 3.4:
Do not automatically generate equivalent alternatives. Do not reuse
previously authored alternatives without author confirmation, except when the
function is known with certainty. [Priority 1]
Techniques:
If the author has
not specified an alternative equivalent, default to leaving out the
relevant attribute, rather than including the attribute with no value or
with automatically-generated content. Leaving out the attribute will
increase the probability that the problem will be detected by checking
algorithms. Refer also to checkpoint 4.1.
If human-authored
equivalent alternatives may be available for an object (for example,
through ATAG checkpoint 3.5 and/or ATAG
checkpoint 3.3), it is appropriate for the tool to offer these to the
author as defaults.
The function of
objects is considered to be known with certainty when they are used
throughout a Web site in a standard way (e.g., graphical navigation
bars). In this case, the objects should have standard alternative
information. Where an object has already been used in a document, the
tool should offer the alternative information that was supplied for the
first or most recent use as a default. If the user changes the
alternative content, they might be asked whether all instances of the
object should have their alternative content updated with the new value.
Note: This checkpoint is priority 3 and is, therefore,
not required to be implemented in order for a tool to conform to ATAG 1.0 at
the single-A and double-AA levels. However, implementing this checkpoint has
the potential to simplify the satisfaction of several higher priority
checkpoints (ATAG checkpoint 3.1, ATAG checkpoint 3.2, and ATAG checkpoint
3.4) and improve the usability of the tool.
Techniques:
Maintain a
registry that associates object identity information with alternative
information (this could be done with the Resource Description Framework
(RDF) [RDF10]). Whenever an object
is used and an equivalent alternative is collected (as per ATAG
checkpoint 3.1) add the object (or identifying information) and the
alternative information to the database. In the case of a text equivalent, the alternate information
may be stored in the document source. For more substantial information
(such as video captions or audio descriptions), the information may be
stored externally and linked from the document source. Allow different
alternative information to be associated with a single object.
Stored alternative
information can be presented to the author as default text in the
appropriate field, whenever one of the associated files is inserted into
the author's document. This satisfies ATAG checkpoint
3.4 because the equivalent alternatives are not automatically
generated and they are only reused with author confirmation.
When no stored
association is found, the field should be left empty (i.e., no purely
rule-generated alternative information should be used).
Note: The term "default" implies that the alternative
information is offered for the author's approval. The term does not imply
that the default alternative information is automatically placed without
the author's approval. Such automatic placement may only occur when in
situations where the function of the object is known with certainty, per
ATAG
checkpoint 3.4. Such a situation might arise in the case of a
"navigation bar builder" that places a navigation bar at the bottom of
every page on a site. In this case, it would be appropriate to use the
same "alt"-text automatically for every instance of a particular image
(with the same target) on every page.
The stored
alternative information required for ATAG
checkpoint 3.3 might be part of the management system, allowing the
alternative equivalents to be retrieved whenever the prepackaged objects
are inserted.
- Tools might allow authors to make keyword searches of a description
database (to simplify the task of finding relevant images, sound files,
etc.). A paper describing a method to
create searchable databases for video and audio files is available
(refer to [SEARCHABLE]).
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