- 1.1 Metadata
- 1.2 Structural grouping
- 2.1 Identifying changes in language
- 2.2 Identifying the primary language
- 3.1 Emphasis
- 3.2 Acronyms and abbreviations
- 3.3 Quotations
- 3.4 Markup and style sheets rather than images: The example of math
- 3.5 Eight other structural elements (to identify citations, code fragments, deleted text, and others)
- 4.1 Use style sheets to change list bullets
- 5.1 Tables of data
- 5.2 Tables for layout
- 5.3 Linearizing tables
- 5.4 Backward compatibility issues for tables
- 6.1 Link text
- 6.2 Grouping and bypassing links
- 6.3 Keyboard access
- 6.4 Anchors and targets
- 7.1 Short text equivalents for images ("alt-text")
- 7.2 Long descriptions of images
- 7.3 Ascii art
- 7.4 Image maps
- 7.5 Color in images
- 7.6 Animated images
- 8.1 Text and non-text equivalents for applets and programmatic objects
- 8.2 Directly accessible applets
- 9.1 Audio information
- 9.2 Text equivalents for multimedia
- 9.3 Embedding multimedia objects
- 10.1 Providing a frame title
- 10.2 Describing frame relationships
- 10.3 Writing for browsers that do not support FRAME
- 10.4 Frame sources
- 10.5 Using FRAME targets
- 10.6 Alternatives to frames
- 11.1 Keyboard access to forms
- 11.2 Grouping form controls
- 11.3 Labeling form controls
- 11.4 Graphical buttons
- 11.5 Techniques for specific controls
- 11.6 Backward compatibility issues for forms
- 12.1 Graceful transformation of scripts
- 12.2 Scripts that cause flickering
- 12.3 Scripts that cause movement and blinking
- 12.4 Directly accessible scripts
- 12.5 Alternative presentation of scripts
- 12.6 Page updates and new windows
- Elements
- Attributes
- 15.1 Other guidelines
- 15.2 User agents and other tools
- 15.3 Accessibility resources
1 Document structure and metadata
Content developers should use structural markup and use it according to specification. Structural elements and attribute (refer to the index of HTML elements and attributes to identify them) promote consistency in documents and supply information to other tools (e.g., indexing tools, search engines, programs that extract tables to databases, navigation tools that use heading elements, and automatic translation software that translates text from one language into another.
1.1 Metadata
Checkpoints in this section:
- 13.2 Provide metadata to add semantic information to pages and sites. [Priority 2]
Some structural elements provide information about the document itself. This is called "metadata" about the document -- metadata is information about data. Well-crafted metadata can provide important orientation information to users. HTML elements that provide useful information about a document include:
1.1.1 TITLE: The document title.
Note that the (mandatory) TITLE element, which only appears once in a document, is different from the "title" attribute, which applies to almost every HTML 4.01 element. Content developers should use the "title" attribute in accordance with the HTML 4.01 specification. For example, "title" should be used with links to provide information about the target of the link.
1.1.2 The ADDRESS element
This element can be used to provide information about the creator of the page.
1.1.3 The META element
Checkpoints in this section:
- 7.4 Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages. [Priority 2] ,
- 7.5 Until user agents provide the ability to stop auto-redirect, do not use markup to redirect pages automatically. Instead, configure the server to perform redirects. [Priority 2] .
This element can specify metadata for a document including keywords, and information about the author. Please refer to the section on automatic page refresh for information on why META should not be used to redirect or auto-refresh pages.
The following are deprecated HTML examples. The first changes the user's page at page at regular intervals. Content developers should not use this technique to simulate "push" technology. Developers cannot predict how much time a user will require to read a page; premature refresh can disorient users. Content developers should avoid periodic refresh and allow users to choose when they want the latest information.
Deprecated example.
. Information.
The following HTML example (using the META element) forwards the user from one page to another after a timeout. However, users should not redirect users with this markup since is non-standard, it disorients users, and it can disrupt a browser's history of visited pages.
Deprecated example.
Don't use this! If your browser supports Refresh, you'll be transported to our new site in 5 seconds, otherwise, select the link manually.
1.1.4 The !DOCTYPE statement
Checkpoints in this section:
- 3.2 Create documents that validate to published formal grammars. [Priority 2]
It is preferable to validate to W3C grammars. Refer to the Technologies Reviewed for Accessibility.
1.1.5 The LINK element and navigation tools
Checkpoints in this section:
- 13.9 Provide information about document collections (i.e., documents comprising multiple pages.). [Priority 3]
Content developers should use the LINK element and link types (refer to [HTML4] , section 6.12) to describe document navigation mechanisms and organization. Some user agents may synthesize navigation tools or allow ordered printing of a set of documents based on such markup.
The following LINK elements might be included in the head of chapter 2 of a book:
1.1.6 The LINK element and alternative documents
Checkpoints in this section:
- 6.5 Ensure that dynamic content is accessible or provide an alternative presentation or page. [Priority 2]
The LINK element may also be used to designate alternative documents. Browsers should load the alternative page automatically based on the user's browser type and preferences. For example, use the LINK element as follows:
Example.
User agents that support LINK will load the alternative page for those users whose browsers may be identified as supporting "aural","braille", or "tty" rendering.
Welcome to the Virtual Mall! .
1.2 Structural grouping
Checkpoints in this section:
- 12.3 Divide large blocks of information into more manageable groups where natural and appropriate. [Priority 2]
The following HTML 4.01 mechanisms group content and make it easier to understand.:
- Use FIELDSET to group form controls into semantic units and describe the group with the LEGEND element.
- Use OPTGROUP to organize long lists of menu options into smaller groups..
- Use tables for tabular data and describe the table with CAPTION.
- Group table rows and columns with THEAD, TBODY, TFOOT, and COLGROUP.
- Nest lists with UL, OL, and DL.
- Use section headings (H1 - H6) to create structured documents and break up long stretches of text. Refer to the following section for more information.
- Break up lines of text into paragraphs (with the P element).
- Group related links. Refer to the section Grouping and bypassing links
All of these grouping mechanisms should be used when appropriate and natural, i.e., when the information lends itself to logical groups. Content developers should not create groups randomly, as this will confuse all users.
1.2.1 Section headings
Checkpoints in this section:
- 3.5 Use header elements to convey document structure and use them according to specification. [Priority 2]
Long documents are often divided into a variety of chapters, chapters have subtopics and subtopics are divided into various sections, sections into paragraphs, etc. These semantic chunks of information make up the structure of the document.
Sections should be introduced with the HTML heading elements ( H1-H6). Other markup may complement these elements to improve presentation (e.g., the HR element to create a horizontal dividing line), but visual presentation is not sufficient to identify document sections.
Since some users skim through a document by navigating its headings, it is important to use them appropriately to convey document structure. Users should order heading elements properly. For example, in HTML, H2 elements should follow H1 elements, H3 elements should follow H2 elements, etc. Content developers should not "skip" levels (e.g., H1 directly to H3). Do not use headings to create font effects; use style sheets to change font styles for example.
Note that in HTML, heading elements (H1 - H6) only start sections, they don't contain them as element content. The following HTML markup shows how style sheets may be used to control the appearance of a heading and the content that follows:
Cooking techniques /* Indent heading and following content */ DIV.section2Cooking techniques
. some text here .Cooking with oil
. text of the section .Cooking with butter
. text of the section .
2 Language information
2.1 Identifying changes in language
Checkpoints in this section:
- 4.1 Clearly identify changes in the natural language of a document's text and any text equivalents (e.g., captions). [Priority 1]
And with a certain je ne sais quoi, she entered both the room, and his life, forever.My name is Natasha,she said.Piacere,he replied in impeccable Italian, locking the door.
Identifying changes in language are important for a number of reasons:
- Users who are reading the document in braille will be able to substitute the appropriate control codes (markup) where language changes occur to ensure that the braille translation software will generate the correct characters (accented characters, for instance). These control codes also prevent braille contractions from being generated, which could further confuse the user. Braille contractions combine commonly used groups of characters that usually appear in multiple cells into a single cell. For example, "ing" which usually takes up three cells (one for each character) can be contracted into a single cell.
- Similarly, speech synthesizers that "speak" multiple languages will be able to generate the text in the appropriate accent with proper pronunciation. If changes are not marked, the synthesizer will try its best to speak the words in the primary language it works in. Thus, the French word for car, "voiture" would be pronounced "voter" by a speech synthesizer that uses English as its primary language.
- Users who are unable to translate between languages themselves, will be able to have unfamiliar languages translated by machine translators.
2.2 Identifying the primary language
Checkpoints in this section:
- 4.3 Identify the primary natural language of a document. [Priority 3]
It is also good practice to identify the primary language of a document, either with markup (as shown below) or through HTTP headers.
. rest of an HTML document written in French.
3 Text markup
The following sections discuss ways to add structure to pieces of text.
3.1 Emphasis
Checkpoints in this section:
- 3.3 Use style sheets to control layout and presentation. [Priority 2]
The proper HTML elements should be used to mark up emphasis: EM and STRONG. The B and I elements should not be used; they are used to create a visual presentation effect. The EM and STRONG elements were designed to indicate structural emphasis that may be rendered in a variety of ways (font style changes, speech inflection changes, etc.)
3.2 Acronyms and abbreviations
Checkpoints in this section:
- 4.2 Specify the expansion of each abbreviation or acronym in a document where it first occurs. [Priority 3]
Example.
Welcome to the WWW!
Example.
.First name SS# . 3.3 Quotations
Checkpoints in this section:
- 3.7 Mark up quotations. Do not use quotation markup for formatting effects such as indentation. [Priority 2]
The Q and BLOCKQUOTE elements mark up inline and block quotations, respectively.
Example.
This example marks up a longer quotation with BLOCKQUOTE:
Remuneration! O! that's the Latin word for three farthings. --- William Shakespeare (Love's Labor Lost).
3.4 Markup and style sheets rather than images: The example of math
Checkpoints in this section:
- 3.1 When an appropriate markup language exists, use markup rather than images to convey information. [Priority 2]
Using markup (and style sheets) where possible rather than images (e.g., a mathematical equation) promotes accessibility for the following reasons:
- Text may be magnified or interpreted as speech or braille.
- Search engines can use text information.
As an example, consider these techniques for putting mathematics on the Web:
- Ensure that users know what variables represent, for example, in the equation "F = m * a", indicate that F= Force, m = mass, a = acceleration.
- For straightforward equations, use characters, as in "x + y = z"
- For more complex equations, mark them up with MathML ( [MATHML] ) or TeX. Note. MathML can be used to create very accessible documents but currently is not as widely supported or used as TeX.
- Provide a text description of the equation and, where possible, use character entity references to create the mathematical symbols. A text equivalent must be provided if the equation is represented by one or more images.
TeX is commonly used to create technical papers which are then converted to HTML for publication on the Web. However, converters tend to generate images, use deprecated markup, and use tables for layout. Consequently, content providers should:
- Make the original TeX (or LaTeX) document available on the Web. There is a system called "AsTeR" ( [ASTER] ) that can create an auditory rendition of TeX and LaTeX documents. Also, IBM has a plug-in for Netscape and Internet Explorer that reads TeX/LaTeX documents and some of MathML (refer to [HYPERMEDIA] ). Note. These tools work primarily in the English environment and may not work so well with speech synthesizers whose primary language is not English.
- Ensure that the HTML created by the conversion process is accessible. Provide a single description of the equation (rather than "alt" text on every generated image as there may be small images for bits and pieces of the equation).
3.5 Eight other structural elements (to identify citations, code fragments, deleted text, and others)
The HTML 4.01 specification defines the following structural elements for miscellaneous markup needs:
CITE Contains a citation or a reference to other sources. DFN Indicates that this is the defining instance of the enclosed term. CODE Designates a fragment of computer code. SAMP Designates sample output from programs, scripts, etc. KBD Indicates text to be entered by the user. VAR Indicates an instance of a variable or program argument. INS Indicates text inserted into a document. DEL Indicates text deleted from a document.
4 Lists
Checkpoints in this section:
- 3.6 Mark up lists and list items properly. [Priority 2]
The HTML list elements DL, UL, and OL should only be used to create lists, not for formatting effects such as indentation. Refer to information on CSS and tables for layout in the CSS Techniques [WCAG10-CSS-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 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.
[CSS1] and [CSS2] allow users to control number styles (for all lists, not just ordered) through user style sheets.
Example.
The following CSS2 style sheet 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.
UL, OL < counter-reset: item >LI < display: block >LI:beforeUntil either CSS2 is widely supported or user agents allow users to control rendering of lists through other means, authors should consider providing contextual clues in unnumbered nested lists. Non-visual users may have difficulties knowing where a list begins and ends and where each list item starts. For example, if a list entry wraps to the next line on the screen, it may appear to be two separate items in the list. This may pose a problem for legacy screen readers.
4.1 Use style sheets to change list bullets
To change the "bullet" style of unordered list items created with the LI element, use style sheets. In CSS, it is possible to specify a fallback bullet style (e.g., 'disc') if a bullet image cannot be loaded.
Example.
To further ensure that users understand differences between list items indicated visually, content developers should provide a text label before or after the list item phrase:
Example.
In this example, new information is communicated through text ("New"), font style (bold), and color (yellow bullet, red text on yellow background).
4.1.1 Images used as bullets
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
Avoid using images as bullets in definition lists created with DL, DT, and DD. However, if this method is used, be sure to provide a text equivalent for the images.
Deprecated example.
Deprecated example using image in DL lists Audrey Laurie Alice
Content developers should avoid list styles where bullets provide additional (visual) information. However, if this is done, be sure to provide a text equivalent describing meaning of the bullet:
Deprecated example.
- Roth IRA
- 401(k)
5 Tables
This section discusses the accessibility of tables and elements that one can put in a TABLE element. Two types of tables are discussed: tables used to organize data, and tables used to create a visual layout of the page.
5.1 Tables of data
Content developers may make HTML 4.01 data tables more accessible in a number of ways:
- Providing summary information
- Identifying row and column information
5.1.1 Providing summary information
Checkpoints in this section:
- 5.5 Provide summaries for tables. [Priority 3]
- 5.6 Provide abbreviations for header labels. [Priority 3]
- Provide a caption via the CAPTION element. A table caption describes the nature of the table in one to three sentences. Two examples:
A caption may not always be necessary.
- "Cups of coffee consumed by each senator."
- "Who spends the most on pollution cleanup?"
- If a CAPTION is not provided, use the "title" attribute on the TABLE element to describe the nature of the table in a few words.
- Provide a summary via the "summary" attribute. Summaries are especially useful for non-visual readers. A summary of the relationships among cells is especially important for tables with nested headings, cells that span multiple columns or rows, or other relationships that may not be obvious from analyzing the structure of the table but that may be apparent in a visual rendering of the table. A summary may also describe how the table fits into the context of the current document. If no caption is provided, it is even more critical to provide a summary. Two examples:
- "This table charts the number of cups of coffee consumed by each senator, the type of coffee (decaf or regular), and whether taken with sugar."
- "Total required by pollution control standards as of January 1, 1971. Commercial category includes stores, insurance companies and banks. The table is divided into two columns. The left-hand column is 'Total investment required in billions of dollars'. The right--hand column is 'Spending' and is divided into three sub-columns. The first sub-column is titled '1970 actual in millions of dollars', the second is '1971 planned in millions of dollars', and the third is 'Percent change, 1970 versus 1971.' The rows are industries." [NBA, 1996].
- Provide terse substitutes for header labels with the " abbr" attribute on TH. These will be particularly useful for future speaking technologies that can read row and column labels for each cell. Abbreviations cut down on repetition and reading time.
5.1.2 Identifying rows and column information
Checkpoints in this section:
- 5.1 For data tables, identify row and column headers. [Priority 1]
- 5.2 For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells. [Priority 1]
Example.
- Identify structural groups of rows (THEAD for repeated table headers, TFOOT for repeated table footers, and TBODY for other groups of rows) and groups of columns (COLGROUP and COL).
- Label table elements with the "scope", " headers", and "axis" attributes so that future browsers and assistive technologies will be able to select data from a table by filtering on categories.
- Do not use PRE to create a tabular layout of text -- use the TABLE element so that assistive technologies may recognize that it is a table.
- For information about table headers, refer to the table header algorithm and discussion in the HTML 4.01 Recommendation ( [HTML4] , section 11.4.3).
This example shows how to associate data cells (created with TD) with their corresponding headers by means of the " headers" attribute. The "headers" attribute specifies a list of header cells (row and column labels) associated with the current data cell. This requires each header cell to have an "id" attribute.
Cups of coffee consumed by each senator Name Cups Type of Coffee Sugar? T. Sexton 10 Espresso No J. Dinnen 5 Decaf Yes A speech synthesizer might render this tables as follows:
Caption: Cups of coffee consumed by each senator Summary: This table charts the number of cups of coffee consumed by each senator, the type of coffee (decaf or regular), and whether taken with sugar. Name: T. Sexton, Cups: 10, Type: Espresso, Sugar: No Name: J. Dinnen, Cups: 5, Type: Decaf, Sugar: YesA visual user agent might render this table as follows:
The next example associates the same header (TH) and data (TD) cells as before, but this time uses the " scope" attribute rather than " headers". "Scope" must have one of the following values: "row", "col", "rowgroup", or "colgroup." Scope specifies the set of data cells to be associated with the current header cell. This method is particularly useful for simple tables. It should be noted that the spoken rendering of this table would be identical to that of the previous example. A choice between the "headers" and "scope" attributes is dependent on the complexity of the table. It does not affect the output so long as the relationships between header and data cells are made clear in the markup.
Example.
Cups of coffee consumed by each senator Name Cups Type of Coffee Sugar? T. Sexton 10 Espresso No J. Dinnen 5 Decaf Yes The following example shows how to create categories within a table using the "axis" attribute.
Example.
Travel Expense Report Meals Hotels Transportsubtotals San Jose25-Aug-97 37.74 112.00 45.00 26-Aug-97 27.28 112.00 45.00 subtotals 65.02 224.00 90.00 379.02 Seattle 27-Aug-97 96.25 109.00 36.00 28-Aug-97 35.00 109.00 36.00 subtotals 131.25 218.00 72.00 421.25 Totals 196.27 442.00 162.00 800.27 This table lists travel expenses at two locations: San Jose and Seattle, by date, and category (meals, hotels, and transport). The following image shows how a visual user agent might render it. [Description of travel table]
5.2 Tables for layout
Checkpoints in this section:
- 5.3 Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version). [Priority 2]
- 5.4 If a table is used for layout, do not use any structural markup for the purpose of visual formatting. [Priority 2]
Authors should use style sheets for layout and positioning. However, when it is necessary to use a table for layout, the table must linearize in a readable order. When a table is linearized, the contents of the cells become a series of paragraphs (e.g., down the page) one after another. Cells should make sense when read in row order and should include structural elements (that create paragraphs, headings, lists, etc.) so the page makes sense after linearization.
Also, when using tables to create a layout, do not use structural markup to create visual formatting. For example, the TH (table header) element, is usually displayed visually as centered, and bold. If a cell is not actually a header for a row or column of data, use style sheets or formatting attributes of the element.
5.3 Linearizing tables
Checkpoints in this section:
- 10.3 Until user agents (including assistive technologies) render side-by-side text correctly, provide a linear text alternative (on the current page or some other) for all tables that lay out text in parallel, word-wrapped columns. [Priority 3]
Tables used to lay out pages where cell text wraps pose problems for older screen readers that do not interpret the source HTML or browsers that do not allow navigation of individual table cells. These screen readers will read across the page, reading sentences on the same row from different columns as one sentence.
For example, if a table is rendered like this on the screen:
There is a 30% chance of Classes at the University of Wisconsin rain showers this morning, but they will resume on September 3rd. should stop before the weekend.This might be read by a screen reader as:
There is a 30% chance of Classes at the University of Wisconsin rain showers this morning, but they will resume on September 3rd. should stop before the weekend.Screen readers that read the source HTML will recognize the structure of each cell, but for older screen readers, content developers may minimize the risk of word wrapping by limiting the amount of text in each cell. Also, the longest chunks of text should all be in the last column (rightmost for left-to-right tables). This way, if they wrap, they will still be read coherently. Content developers should test tables for wrapping with a browser window dimension of "640x480".
Since table markup is structural, and we suggest separating structure from presentation, we recommend using style sheets to create layout, alignment, and presentation effects. Thus, the two columns in the above example could have been created using style sheets. Please refer to the section on style sheets for more information.
It is usually very simple to linearize a table used to layout a page - simply strip the table markup from the table. There are several tools that do this, and it is becoming more common for screen readers and some browsers to linearize tables.
However, linearizing data tables requires a different strategy. Since data cells rely on the information provided by surrounding and header cells, the relationship information that is available visually needs to be translated into the linear table.
For example, specify the column layout order. The natural language writing direction may affect column layout and thus the order of a linearized table. The "dir" attribute specifies column layout order (e.g., dir="rtl" specifies right-to-left layout).
@@also the case for layout tables?
@@again, there are tools to help produce linearized versions of data tables. We will provide a link
This markup will also help browsers linearize tables (also called table "serialization"). A row-based linear version may be created by reading the row header, then preceding each cell with the cell's column header. Or, the linearization might be column-based. Future browsers and assistive technologies will be able to automatically translate tables into linear sequences or navigate a table cell by cell if data is labeled appropriately. The WAI Evaluation and Repair working group is tracking the progress of tools as well as developing their own that will allow users to linearize or navigate tables cell by cell. Refer to [WAI-ER] .
Quicktest! To get a better understanding of how a screen reader would read a table, run a piece of paper down the page and read your table line by line.
5.4 Backward compatibility issues for tables
@@checkpoint that this can fit under?In HTML 3.2 browsers, the rows of a TFOOT element will appear before the table body.
6 Links
6.1 Link text
Checkpoints in this section:
- 13.1 Clearly identify the target of each link. [Priority 2]
Good link text should not be overly general; don't use "click here." Not only is this phrase device-dependent (it implies a pointing device) it says nothing about what is to be found if the link if followed. Instead of "click here", link text should indicate the nature of the link target, as in "more information about sea lions" or "text-only version of this page". Note that for the latter case (and other format- or language-specific documents), content developers are encouraged to use content negotiation instead, so that users who prefer text versions will have them served automatically.
In addition to clear link text, content developers may specify a value of the "title" attribute that clearly and accurately describes the target of the link.
"Auditory users" -- people who are blind, have difficulty seeing, or who are using devices with small or no displays -- are unable to scan the page quickly with their eyes. To get an overview of a page or to quickly find a link, these users will often tab from one link to the next or review a list of available links on a page.
Thus, for a series of related links, include introductory information in the first link, then distinguishing information in the links that follow. This will provide context information for users reading them in sequence.
Example.
My document is available in HTML, PDF, plain text6.1.1 Text for images used as links
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
When an image is used as the content of a link, specify a text equivalent for the image.
Example.
Or, if you provide link text, use a space as the "alt" attribute value of the IMG element. Note that this text will appear on the page next to the image.
Example.
6.2 Grouping and bypassing links
Checkpoints in this section:
- 13.6 Group related links, identify the group (for user agents), and, until user agents do so, provide a way to bypass the group. [Priority 3]
- 10.5 Until user agents (including assistive technologies) render adjacent links distinctly, include non-link, printable characters (surrounded by spaces) between adjacent links. [Priority 3]
When links are grouped into logical sets (for example, in a navigation bar that appears on every page in a site) they should be marked up as a unit. Navigation bars are usually the first thing someone encounters on a page. For users with speech synthesizers, this means having to hear a number of links on every page before reaching the interesting content of a page. There are several ways to allow users to bypass groups of links (as users with vision do when they see the same set on each page):
- Include a link that allows users to skip over the set of navigation links. Use the HTML 4.01 "tabindex" attribute to allow users to jump to an anchor after the set of navigation links. This attribute is not yet widely supported.
- Provide a style sheet that allows users to hide the set of navigation links.
- Use the HTML 4.01 MAP element to group links, then identify the group with the "title" attribute.
In the future, user agents may allow users to skip over elements such as navigation bars.
Example.
In this example, the MAP element groups a set of links, the "title" attribute identifies it as a navigation bar , and a link at the beginning of the group links to the anchor after the group. Also, note that the links are separated by non-link, printable characters (surrounded by spaces).
How to use our site
6.3 Keyboard access
Checkpoints in this section:
- 9.4 Create a logical tab order through links, form controls, and objects. [Priority 3]
- 9.5 Provide keyboard shortcuts to important links (including those in client-side image maps), form controls, and groups of form controls. [Priority 3]
Example.
In this example, if the user activates the "C" key, the link will be followed.
Note: Until user agents provide an overview of which key bindings are available, provide information on the key bindings.
6.4 Anchors and targets
Checkpoints in this section:
- 10.1 Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user. [Priority 2]
7 Images and image maps
The following sections discuss accessibility of images (including simple animations such as GIF animations) and image maps.
7.1 Short text equivalents for images ("alt-text")
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1] .
When using IMG, specify a short text equivalent with the "alt" attribute. Note. The value of this attribute is referred to as "alt-text".
Example.
When using OBJECT, specify a text equivalent in the body of the OBJECT element:
Example.
7.2 Long descriptions of images
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
When a short text equivalent does not suffice to adequately convey the function or role of an image, provide additional information in a file designated by the "longdesc" attribute:
Example.
A chart showing how sales in 1997 progressed. The chart
is a bar-chart showing percentage increases in sales
by month. Sales in January were up 10% from December 1996,
sales in February dropped 3%, ..Example.
When using OBJECT, specify longer text equivalent within the element's content:
Example.
Note that OBJECT content, unlike "alt" text, can include markup. Thus, content developers can provide a link to additional information from within the OBJECT element:
Example.
7.2.1 Invisible d-links
Note. Invisible d-links are deprecated in favor of the "longdesc" attribute.
An invisible d-link is a small (1-pixel) or transparent image whose " alt" attribute value is "D-link" or "D" and is part of the content of an A element. Like other d-links, it refers to a text equivalent of the associated image. Like other links, users can tab to it. Invisible d-links thus provide a (temporary) solution for designers who wish to avoid visible d-links for stylistic reasons.
7.3 Ascii art
Checkpoints in this section:
- 13.10 Provide a means to skip over multi-line ASCII art. [Priority 3]
Avoid ASCII art (character illustrations) and use real images instead since it is easier to supply a text equivalent for images. However, if ASCII art must be used provide a link to jump over the ASCII art, as follows.
Example.
skip over ASCII art caption for ASCII artASCII art may also be marked up as follows [skip over ASCII figure or consult a description of chart]:
Example.
% __ __ __ __ __ __ __ __ __ __ __ __ __ __ 100 | * | 90 | * * | 80 | * * | 70 | @ * | 60 | @ * | 50 | * @ * | 40 | @ * | 30 | * @ @ @ * | 20 | | 10 | @ @ @ @ @ | 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Flash frequency (Hz)Example.
If the ASCII art is complex, ensure that the text equivalent adequately describes it.
Another way to replace ASCII art is to use human language substitutes. For example, might substitute for a winking smiley: ;-) . Or, the word "therefore" can replace arrows consisting of dashes and greater than signs (e.g., -->), and the word "great" for the uncommon abbreviation "gr8".
7.4 Image maps
An image map is an image that has "active regions". When the user selects one of the regions, some action takes place -- a link may be followed, information may be sent to a server, etc. To make an image map accessible, content developers must ensure that each action associated with a visual region may be activated without a pointing device.
Image maps are created with the MAP element. HTML allows two types of image maps: client-side (the user's browser processes a URI) and server-side (the server processes click coordinates). For all image maps, content developers must supply a text equivalent.
Content developers should create client-side image maps (with " usemap") rather than server-side image maps (with " ismap") because server-side image maps require a specific input device. If server-side image maps must be used (e.g., because the geometry of a region cannot be represented with values of the shape attribute), authors must provide the same functionality or information in an alternative accessible format. One way to achieve this is to provide a textual link for each active region so that each link is navigable with the keyboard. If you must use a server-side image map, please consult the section on server-side image maps
7.4.1 Text equivalents for client-side image maps
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
Provide text equivalents for image maps since they convey visual information. As with other links, the link text should make sense when read out of context. Refer to the section on Link Text for information on writing good link text. Users may also want keyboard shortcuts to access frequently followed links. Refer to the section on Keyboard access to links.
Example.
The following example illustrates the same idea, but uses OBJECT instead of IMG to insert the image to provide more information about the image:
Example.
7.4.2 Redundant text links for client-side image maps
Checkpoints in this section:
- 1.5 Until user agents render text equivalents for client-side image map links, provide redundant text links for each active region of a client-side image map. [Priority 3]
In addition to providing a text equivalent, provide redundant textual links. If the A element is used instead of AREA, the content developer may describe the active regions and provide redundant links at the same time:
Note that in the previous example, the MAP element is the content of the OBJECT element so that the alternative links will only be displayed if the image map (navbar1.gif) is not.
Note also that links have been separated by brackets ([]). This is to prevent older screen readers from reading several adjacent links as a single link as well as to help sighted users distinguish between links visually.
7.4.3 Client-side versus server-side image maps
Checkpoints in this section:
- 9.1 Provide client-side image maps instead of server-side image maps except where the regions cannot be defined with an available geometric shape. [Priority 1]
7.4.4 Server-side image maps
Checkpoints in this section:
- 1.2 Provide redundant text links for each active region of a server-side image map. [Priority 1]
When a server-side image map must be used, content developers should provide an alternative list of image map choices. There are three techniques:
Example.
- Include the alternative links within the body of an OBJECT element (refer to the previous example illustrating links in the OBJECT element).
- If IMG is used to insert the image, provide an alternative list of links after it and indicate the existence and location of the alternative list (e.g., via that "alt" attribute).
[Reference] [Audio Visual Lab]End example.7.5 Color in images
Checkpoints in this section:
- 2.2 Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen. [Priority 2 for images, Priority 3 for text].
7.6 Animated images
Checkpoints in this section:
- 7.3 Until user agents allow users to freeze moving content, avoid movement in pages. [Priority 2]
8 Applets and other programmatic objects
8.1 Text and non-text equivalents for applets and programmatic objects
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
- 6.2 Ensure that equivalents for dynamic content are updated when the dynamic content changes. [Priority 1]
- 6.3 Ensure that pages are usable when scripts, applets, or other programmatic objects are turned off or not supported. If this is not possible, provide equivalent information on an alternative accessible page. [Priority 1]
If OBJECT is used, provide a text equivalent in the content of the element:
Example.
A more complex example takes advantage of the fact the OBJECT elements may be embedded to provide for alternative representations of information:
Example.
If APPLET is used, provide a text equivalent with the "alt" attribute and in the content in the APPLET element. This enables the content to transform gracefully for those user agents that only support one of the two mechanisms ("alt" or content).
Deprecated example.
8.2 Directly accessible applets
Checkpoints in this section:
- 8.1 Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies [Priority 1 if functionality is important and not presented elsewhere, otherwise Priority 2.]
If an applet (created with either OBJECT or APPLET) requires user interaction (e.g., the ability to manipulate a physics experiment) that cannot be duplicated in an alternative format, make the applet directly accessible.
If an applet creates motion, developers should provide a mechanism for freezing this motion (for an example, refer to [TRACE] ). Also, please refer to the next section for information about making audio and video presentations accessible.
For more information about developing accessible applets, please refer to [JAVAACCESS] and [IBMJAVA] . These companies have been developing an Accessibility API as well as making the Java Swing classes accessible.
- 3.4 Use relative rather than absolute units in markup language attribute values and style sheet property values. [Priority 2] ,
- 6.4 For scripts and applets, ensure that event handlers are input device-independent. [Priority 2] ,
- 6.5 Ensure that dynamic content is accessible or provide an alternative presentation or page. [Priority 2] ,
- 7.1 Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1] ,
- 7.2 Until user agents allow users to control blinking, avoid causing content to blink (i.e., change presentation at a regular rate, such as turning on and off). [Priority 2] ,
- 7.3 Until user agents allow users to freeze moving content, avoid movement in pages. [Priority 2] ,
- 7.4 Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages. [Priority 2] ,
- 9.2 Ensure that any element that has its own interface can be operated in a device-independent manner. [Priority 2] ,
- and 10.1 Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user. [Priority 2] .
- 1.4 For any time-based multimedia presentation (e.g., a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) with the presentation. [Priority 1]
9 Audio and video
9.1 Audio information
9.2 Text equivalents for multimedia
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
When necessary, a text equivalent should be provided for visual information to enable understanding of the page. For example, consider a repeating animation that shows cloud cover and precipitation as part of a weather status report. Since the animation is supplementing the rest of the weather report (that is presented in natural language - text), a less verbose description of the animation is necessary. However, if the animation appears in a pedagogical setting where students are learning about cloud formations in relation to land mass, then the animation ought to be described for those who can not view the animation but who also want to learn the lesson.
9.3 Embedding multimedia objects
Other objects, such as those requiring a plug-in, should also use the OBJECT element. However, for backward compatibility with Netscape browsers, use the proprietary EMBED element within the OBJECT element as follows:
Deprecated example.
For more information refer to [MACROMEDIA] .
10 Frames
For visually enabled users, frames may organize a page into different zones. For non-visual users, relationships between the content in frames (e.g., one frame has a table of contents, another the contents themselves) must be conveyed through other means.
Frames as implemented today (with the FRAMESET, FRAME, and IFRAME elements) are problematic for several reasons:
- Without scripting, they tend to break the "previous page" functionality offered by browsers.
- It is impossible to refer to the "current state" of a frameset with a URI; once a frameset changes contents, the original URI no longer applies.
- Opening a frame in a new browser window can disorient or simply annoy users.
In the following sections, we discuss how to make frames more accessible. We also provide an alternative to frames that uses HTML 4.01 and CSS and addresses many of the limitations of today's frame implementations.
10.1 Providing a frame title
Checkpoints in this section:
- 12.1 Title each frame to facilitate frame identification and navigation. [Priority 1]
Example.
Use the "title" attribute to name frames.
10.2 Describing frame relationships
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
- 12.2 Describe the purpose of frames and how frames relate to each other if it is not obvious by frame titles alone. [Priority 2]
Example.
Today's news frameset-desc.html might say something like:
#Navbar - this frame provides links to the major sections of the site: World News, National News, Local News, Technological News, and Entertainment News. #Story - this frame displays the currently selected story. #Index - this frame provides links to the day's headline stories within this section.Note that if the a frame's contents change, the text equivalent will no longer apply. Also, links to descriptions of a frame should be provided along with other alternative content in the NOFRAMES element of a FRAMESET.
10.3 Writing for browsers that do not support FRAME
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
- 6.5 Ensure that dynamic content is accessible or provide an alternative presentation or page. [Priority 2]
Example.
In this example, if the user reads "top.html":
and the user agent is not displaying frames, the user will have access (via a link) to a non-frames version of the same information.
10.4 Frame sources
Checkpoints in this section:
- 6.2 Ensure that equivalents for dynamic content are updated when the dynamic content changes. [Priority 1]
Content developers must provide text equivalents of frames so that their contents and the relationships between frames make sense. Note that as the contents of a frame change, so must change any description. This is not possible if an IMG is inserted directly into a frame. Thus, content developers should always make the source ("src") of a frame an HTML file. Images may be inserted into the HTML file and their text alternatives will evolve correctly.
Example.
A correct frameset document Deprecated example.
A bad frameset document Note that if, for example, a link causes a new image to be inserted into the frame:
the initial title of the frame ("Apples") will no longer match the current content of the frame ("Oranges").
10.5 Using FRAME targets
Checkpoints in this section:
- 10.1 Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user. [Priority 2]
Content developers should avoid specifying a new window as the target of a frame with target="_blank".
10.6 Alternatives to frames
One of the most common uses of frames is to split the user's browser window into two parts: a navigation window and a content window. As an alternative to frames, we encourage you to try the following:
Example. OBJECT
- Create one document for the navigation mechanism (call it "nav.html"). A separate document means that the navigation mechanism may be shared by more than one document.
- In each document requiring the navigation mechanism, include it at the bottom of the document with the following (or similar) OBJECT markup:
The following CSS rule attaches the navigation mechanism to the bottom-left corner of the page of the page and keeps it there even if the user scrolls down the page:
OBJECTNote. Navigation mechanisms or other content may be inserted in a document by means of server-side includes.
10.6.1 Sizing frames with relative units
Checkpoints in this section:
- 3.4 Use relative rather than absolute units in markup language attribute values and style sheet property values. [Priority 2]
In the previous examples, note that frame sizes are specified in percentage. When a user resizes the window, the frames will adjust accordingly and remain readable.
11 Forms
This section discusses the accessibility of forms and form controls that one can put in a FORM element.
11.1 Keyboard access to forms
Checkpoints in this section:
- 9.4 Create a logical tab order through links, form controls, and objects. [Priority 3]
- 9.5 Provide keyboard shortcuts to important links (including those in client-side image maps), form controls, and groups of form controls. [Priority 3]
In the next example, we specify a tabbing order among elements (in order, "field2", "field1", "submit") with "tabindex":
Example.
This example assigns "U" as the accesskey (via " accesskey"). Typing "U" gives focus to the label, which in turn gives focus to the input control, so that the user can input text.
Example.
11.2 Grouping form controls
Checkpoints in this section:
- 12.3 Divide large blocks of information into more manageable groups where natural and appropriate. [Priority 2]
Content developers should group information where natural and appropriate. When form controls can be grouped into logical units, use the FIELDSET element and label those units with the LEGEND element:
Example.
11.2.1 Grouping menu options
Content developers should group information where natural and appropriate. For long lists of menu selections (which may be difficult to track), content developers should group SELECT items (defined by OPTION) into a hierarchy using the OPTGROUP element. Specifies a label for the group of options with the label attribute on OPTGROUP.
Example.
11.3 Labeling form controls
Checkpoints in this section:
- 12.4 Associate labels explicitly with their controls. [Priority 2]
- 10.2 Until user agents support explicit associations between labels and form controls, for all form controls with implicitly associated labels, ensure that the label is properly positioned. [Priority 2]
An example of LABEL used with " for" in HTML 4.01 is given in the previous section.
A label is implicitly associated with its form control either through markup or positioning on the page. The following example shows how a label and form control may be implicitly associated with markup.
Example.
First name:11.4 Graphical buttons
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
However, a graphical form submit button created with INPUT, type="image" creates a type of server-side image map. Whenever the button is clicked with a mouse, the x and y coordinates of the mouse click are sent to the server as part of the form submission.
- Use multiple submit buttons (each with its own image) in place of a single graphical submit button. Authors may use style sheets to control the positioning of these buttons.
- Use a client-side image map together with scripting.
11.5 Techniques for specific controls
Checkpoints in this section:
- 10.4 Until user agents handle empty controls correctly, include default, place-holding characters in edit boxes and text areas. [Priority 3]
Example.
Some legacy assistive technologies require initial text in form controls such as TEXTAREA in order to function properly.
Provide a text equivalent for images used as "submit" buttons:
Example.
Also refer to the section on keyboard access since this applies to form controls.
11.6 Backward compatibility issues for forms
In some HTML 3.2 browsers,
- The BUTTON element does not appear
- INPUT with type="button" will appear as a text input field
12 Scripts
This section discusses the accessibility of scripts included in a document via the SCRIPT element. @@this section needs work. plus, is this the best place for this discussion? should we have a separate "non-w3c" module?
12.1 Graceful transformation of scripts
Checkpoints in this section:
- 6.5 Ensure that dynamic content is accessible or provide an alternative presentation or page. [Priority 2]
Content developers must ensure that pages are accessible with scripts turned off or in browsers that don't support scripts.
- Avoid creating content on the fly on the client. If a user's browser does not handle scripts, no content will be generated or displayed. However, this is different than displaying or hiding already existing content by using a combination of style sheets and scripting; if there is no script, then the content is always shown. This also does not rule out generating pages on the fly on the server-side and delivering them to the client.
- Avoid creating links that use "javascript" as the URI. If a user is not using scripts, then they won't be able to link since the browser can't create the link content.
Deprecated example. This is a dead-end link for a user agent where scripts are not supported or not loaded.
End example.12.2 Scripts that cause flickering
Checkpoints in this section:
- 7.1 Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1]
12.3 Scripts that cause movement and blinking
Checkpoints in this section:
- 7.2 Until user agents allow users to control blinking, avoid causing content to blink (i.e., change presentation at a regular rate, such as turning on and off). [Priority 2]
- 7.3 Until user agents allow users to freeze moving content, avoid movement in pages. [Priority 2]
12.4 Directly accessible scripts
Checkpoints in this section:
- 6.4 For scripts and applets, ensure that event handlers are input device-independent. [Priority 2]
- 6.3 Ensure that pages are usable when scripts, applets, or other programmatic objects are turned off or not supported. If this is not possible, provide equivalent information on an alternative accessible page. [Priority 1]
- 8.1 Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies [Priority 1 if functionality is important and not presented elsewhere, otherwise Priority 2.]
- 9.3 For scripts, specify logical event handlers rather than device-dependent event handlers. [Priority 2]
Some event handlers, when invoked, produce purely decorative effects such as highlighting an image or changing the color of an element's text. Other event handlers produce much more substantial effects, such as carrying out a calculation, providing important information to the user, or submitting a form. For event handlers that do more than just change the presentation of an element, content developers should do the following:
- Use application-level event triggers rather than user interaction-level triggers. In HTML 4.01, application-level event attributes are "onfocus", "onblur" (the opposite of "onfocus"), and "onselect". Note that these attributes are designed to be device-independent, but are implemented as keyboard specific events in current browsers.
- Otherwise, if you must use device-dependent attributes, provide redundant input mechanisms (i.e., specify two handlers for the same element):
- Use "onmousedown" with "onkeydown".
- Use "onmouseup" with "onkeyup"
- Use "onclick" with "onkeypress"
Note that there is no keyboard equivalent to double-clicking ("ondblclick") in HTML 4.01.
12.5 Alternative presentation of scripts
Checkpoints in this section:
- 1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
- 6.2 Ensure that equivalents for dynamic content are updated when the dynamic content changes. [Priority 1]
One way to accomplish this is with the NOSCRIPT element. The content of this element is rendered when scripts are not enabled.
Example.
12.6 Page updates and new windows
Checkpoints in this section:
- 7.4 Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages. [Priority 2]
- 7.5 Until user agents provide the ability to stop auto-redirect, do not use markup to redirect pages automatically. Instead, configure the server to perform redirects. [Priority 2]
- 10.1 Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user. [Priority 2]
13 Index of HTML elements and attributes
Checkpoints in this section:
- 11.2 Avoid deprecated features of W3C technologies. [Priority 2]
Elements
This index lists all elements in HTML 4.01. The first column of this table links to the definition of the element in the HTML 4.01 specification ( [HTML4] ). Elements that are deprecated in HTML 4.01 are followed by an asterisk (*). Elements that are obsolete in HTML 4.01 or don't exist in a W3C specification of HTML (2.0, 3.2, 4.01) do not appear in this table.
The second column indicates other W3C specifications for HTML that included each element. The third column indicates the element's role.
The last column lists the sections in the current document where the element is discussed. An entry of "N/A" means that the element is not discussed in this document.
Element name Defined also in Role Techniques A 2.0, 3.2 Structure N/A ABBR Structure N/A ACRONYM Structure N/A ADDRESS 2.0, 3.2 Metadata N/A APPLET* 3.2 Replaced N/A AREA 3.2 Structure N/A B 2.0, 3.2 Presentation N/A BASE 2.0, 3.2 Processing N/A BASEFONT* 3.2 Presentation N/A BDO Processing N/A BIG 3.2 Presentation N/A BLOCKQUOTE 2.0, 3.2 Structure N/A BODY 2.0, 3.2 Structure N/A BR 2.0, 3.2 Presentation N/A BUTTON Structure N/A CAPTION 3.2 Structure N/A CENTER* 3.2 Presentation N/A CITE 2.0, 3.2 Structure N/A CODE 2.0, 3.2 Structure N/A COL Structure N/A COLGROUP Structure N/A DD 2.0, 3.2 Structure N/A DEL Metadata N/A DFN 3.2 Structure N/A DIR* 2.0, 3.2 Structure N/A DIV 3.2 Structure N/A DL 2.0, 3.2 Structure N/A DT 2.0, 3.2 Structure N/A EM 2.0, 3.2 Structure N/A FIELDSET Structure N/A FONT* 3.2 Presentation N/A FORM 2.0, 3.2 Structure N/A FRAME Replaced N/A FRAMESET Presentation N/A H1 2.0, 3.2 Structure N/A HEAD 2.0, 3.2 Structure N/A HR 2.0, 3.2 Presentation N/A HTML 2.0, 3.2 Structure N/A I 2.0, 3.2 Presentation N/A IFRAME Replaced N/A IMG 2.0, 3.2 Replaced N/A INPUT 2.0, 3.2 Structure N/A INS Metadata N/A ISINDEX* 2.0, 3.2 Structure N/A KBD 2.0, 3.2 Structure N/A LABEL Structure N/A LEGEND Structure N/A LI 2.0, 3.2 Structure N/A LINK 2.0, 3.2 Metadata N/A MAP 3.2 Structure N/A MENU* 2.0, 3.2 Structure N/A META 2.0, 3.2 Metadata N/A NOFRAMES Alternative N/A NOSCRIPT Alternative N/A OBJECT Replaced N/A OL 2.0, 3.2 Structure N/A OPTGROUP Structure N/A OPTION 2.0, 3.2 Structure N/A P 2.0, 3.2 Structure N/A PARAM 3.2 Processing N/A PRE 2.0, 3.2 Presentation N/A Q Structure N/A S* Presentation N/A SAMP 2.0, 3.2 Structure N/A SCRIPT 3.2 (DTD) Processing N/A SELECT 2.0, 3.2 Structure N/A SMALL 3.2 Presentation N/A SPAN Structure N/A STRIKE* 3.2 Presentation N/A STRONG 2.0, 3.2 Structure N/A STYLE 3.2 (DTD) Processing N/A SUB 3.2 Presentation N/A SUP 3.2 Presentation N/A TABLE 3.2 Structure N/A TBODY Structure N/A TD 3.2 Structure N/A TEXTAREA 2.0, 3.2 Structure N/A TFOOT Structure N/A TH 3.2 Structure N/A THEAD Structure N/A TITLE 2.0, 3.2 Metadata N/A TR 3.2 Structure N/A TT 2.0, 3.2 Presentation N/A U* 3.2 Presentation N/A UL 2.0, 3.2 Structure N/A VAR 2.0, 3.2 Structure N/A Attributes
This index lists some attributes in HTML 4.01 that affect accessibility and what elements they apply to. The first column of this table links to the definition of the attribute in the HTML 4.01 specification ( [HTML4] ). Attributes and elements that are deprecated in HTML 4.01 ( [HTML4] ) are followed by an asterisk (*). Attributes and elements that are obsolete in HTML 4.01 or don't exist in a W3C specification of HTML (2.0, 3.2, 4.01) do not appear in this table. Attributes that apply to most elements of HTML 4.01 are indicated as such; please consult the HTML 4.01 specification for the exact list of elements with this attribute.
The second column indicates other W3C specifications for HTML that included each attribute. The third column indicates the elements that take each attribute. The fourth column indicates the attribute's role.
The last column lists the sections in the current document where the attribute is discussed. An entry of "N/A" means that the attribute is not discussed in this document.
Attribute name Applies to elements Role Techniques abbr TD, TH Alternative N/A accesskey A, AREA, BUTTON, INPUT, LABEL, LEGEND, TEXTAREA User Interface N/A alt APPLET, AREA, IMG, INPUT Alternative N/A axis TD, TH Structure N/A class Most elements Structure N/A dir Most elements Processing N/A for LABEL Structure N/A headers TD, TH Structure N/A hreflang A, LINK Metadata N/A id Most elements Structure N/A label OPTION Alternative N/A lang Most elements Metadata N/A longdesc IMG, FRAME, IFRAME Alternative N/A scope TD, TH Structure N/A style Most elements Processing N/A summary TABLE Alternative N/A tabindex A, AREA, BUTTON, INPUT, OBJECT, SELECT, TEXTAREA User Interface N/A title Most elements Metadata N/A usemap IMG, INPUT, OBJECT Processing N/A The following is the list of HTML 4.01 attributes not directly related to accessibility. Content developers should use style sheets instead of presentation attributes. For event handler attributes, please refer to the section on device-independent event handlers for more detail.
Other structural attributes: start*, value*, rowspan, colspan, span Other presentation attributes: align*, valign*, clear*, nowrap*, char, charoff, hspace*, vspace*, cellpadding, cellspacing, compact*, face*, size*, background*, bgcolor*, color*, text*, link*, alink*, vlink*, border, noshade*, rules, size (deprecated according to element), marginheight, marginwidth, frame, frameborder, rows, cols Other processing instruction attributes: ismap, coords, shape Other user interface attributes: target, scrolling, noresize Other metadata attributes: type, cite, datetime Event handler attributes: onblur, onchange, onclick, ondblclick, onfocus, onkeydown, onkeypress, onkeyup, onload, onload, onmousedown, onmousemove, onmouseout, onmouseover, onmouseup, onreset, onselect, onsubmit, onunload
14 References
For the latest version of any W3C specification please consult the list of W3C Technical Reports at http://www.w3.org/TR.
[CSS1] "CSS, level 1 Recommendation", B. Bos, H. Wium Lie, eds., 17 December 1996, revised 11 January 1999. This CSS1 Recommendation is http://www.w3.org/TR/1999/REC-CSS1-19990111. The latest version of CSS1 is available at http://www.w3.org/TR/REC-CSS1. [CSS2] "CSS, level 2 Recommendation", B. Bos, H. Wium Lie, C. Lilley, and I. Jacobs, eds., 12 May 1998. This CSS2 Recommendation is http://www.w3.org/TR/1998/REC-CSS2-19980512/. The latest version of CSS2 is available at http://www.w3.org/TR/REC-CSS2. [HTML4] "HTML 4.01 Recommendation", D. Raggett, A. Le Hors, and I. Jacobs, eds., 24 December 1999. This HTML 4.01 Recommendation is http://www.w3.org/TR/1999/REC-html401-19991224/. [MATHML] "Mathematical Markup Language", P. Ion and R. Miner, eds., 7 April 1998, revised 7 July 1999. This MathML 1.0 Recommendation is http://www.w3.org/TR/1998/REC-MathML-19990707/. The latest version of MathML 1.0 is available at http://www.w3.org/TR/REC-MathML. [WCAG10] "Web Content Accessibility Guidelines 1.0", W. Chisholm, G. Vanderheiden, and I. Jacobs, eds., 5 May 1999. This WCAG 1.0 Recommendation is http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/. [WCAG10-CSS-TECHNIQUES] "CSS Techniques for Web Content Accessibility Guidelines 1.0", W. Chisholm, G. Vanderheiden, and I. Jacobs, eds. The latest version of this document is available at http://www.w3.org/TR/WCAG10-CSS-TECHS/. [WCAG10-TECHS] "Techniques for Web Content Accessibility Guidelines 1.0", W. Chisholm, G. Vanderheiden, I. Jacobs, eds. This document explains how to implement the checkpoints defined in "Web Content Accessibility Guidelines 1.0". The latest draft of the techniques is available at http://www.w3.org/TR/WCAG10-TECHS/.
15 Resources
Note: W3C does not guarantee the stability of any of the following references outside of its control. These references are included for convenience. References to products are not endorsements of those products.
15.1 Other guidelines
15.2 User agents and other tools
A list of alternative Web browsers (assistive technologies and other user agents designed for accessibility) is maintained at the WAI Web site.
15.3 Accessibility resources
16 Acknowledgments
Web Content Guidelines Working Group Co-Chairs: Jason White, University of Melbourne Gregg Vanderheiden, Trace Research and Development W3C Team contact: Wendy Chisholm We wish to thank the following people who have contributed their time and valuable comments to shaping these guidelines: Harvey Bingham, Kevin Carey, Chetz Colwell, Neal Ewers, Geoff Freed, Al Gilman, Larry Goldberg, Jon Gunderson, Eric Hansen, Phill Jenkins, Leonard Kasday, George Kerscher, Marja-Riitta Koivunen, Josh Krieger, Chuck Letourneau, Scott Luebking, William Loughborough, Murray Maloney, Charles McCathieNevile, MegaZone (Livingston Enterprises), Masafumi Nakane, Mark Novak, Charles Oppermann, Mike Paciello, David Pawson, Michael Pieper, Greg Rosmaita, Liam Quinn, Dave Raggett, T.V. Raman, Robert Savellis, Jutta Treviranus, Steve Tyler, and Jaap van Lelieveld
