http://www.danidesaro.com - WCAG 2.0 AA

The CSS background-image property provides a way to include images in the document with CSS without any reference in the HTML code. The CSS background-image property was designed for decorative purposes and it is not possible to associate text alternatives with images that are included via CSS. Text alternatives are necessary for people who cannot see images that convey important information. Therefore, it is a failure to use this property to add images to convey important information.

This describes a failure condition for all techniques involving text alternatives. If the text in the "text alternative" cannot be used in place of the non-text content without losing information or function then it fails because it is not, in fact, an alternative to the non-text content. For example the alt text is the same as the item image name is graph.jpg and the alt text is graph.jpg

This objective of this technique is to avoid unnecessary duplication that occurs when adjacent text and iconic versions of a link are contained in a

When using the img element, specify a short text alternative with the alt attribute. Note. The value of this attribute is referred to as "alt text".

The objective of this technique is to use the label element to explicitly associate a form control with a label. A label is attached to a specific form control through the use of the for attribute. The value of the for attribute must be the same as the value of the id attribute of the form control.

The objective of this technique is to describe the failure that occurs when the long deion for non-text content does not serve the same purpose or does not present the same information as the non-text content. This can cause problems for people who cannot interpret the non-text content because they rely on the long deion to provide the necessary information conveyed by the non-text content. Without a long deion that provides complete information, a person may not be able to comprehend or interact with the Web page.

The purpose of this technique is to reduce occasions in which a user with a disability cannot complete a CAPTCHA task. Because there are alternate CAPTCHA tasks that use different modalities, a user is more likely to be able to complete one of the tasks successfully.

The objective of this technique is to provide text alternatives that serve the same purpose as the selectable regions of an image map. An image map is an image divided into selectable regions defined by area elements. Each area is a link to another Web page or another part of the current Web page. The alt attribute of each area element serves the same purpose as the selectable area of the image.

If object is used, provide a text alternative in the content of the element:

Provide a text alternative for an applet by using the alt attribute to label an applet and providing the text alternative in the body of the applet element. Both mechanisms are required due to the varying support of the alt attribute and applet body text by user agents.

For input elements of type 'image', the alt attribute of the input element is used to provide a functional label. This label indicates the button's function, but does not attempt to describe the image. The label is especially important if there are multiple submit buttons on the page that each lead to different results.

The objective of this technique is to provide information in a file designated by thelongdesc attribute when a short text alternative does not adequately convey the function or information provided in the image. The longdesc attribute is a URI, the target of which contains a long deion of the non-text content.

EMBED elements present functionality not available to all users. The NOEMBED element can be used to provide a deion.

The objective of this technique is to provide a text alternative for content rendered using the object element. The body of the object element can be used to provide a complete text alternative for the object or may contain additional non-text content with text alternatives.

The objective of this technique is to use the title attribute to label form controls when the visual design cannot accommodate the label (for example, if there is no text on the screen that can be identified as a label) or where it might be confusing to display a label. User agents, including assistive technology, can speak the title attribute.

The purpose of this technique is to show how images can be marked so that they can be ignored by Assistive Technology.

The objective of this technique is to show how identifying content only by its shape or location makes content difficult to understand and operate. When only visual identification or location is used, users with visual disabilities may find it difficult to locate content since they cannot see the screen or may perceive only a small portion of the screen at one time. Also, location of content can vary if page layout varies due to variations in font, window, or screen size.

The objective of this technique is to ensure that when color differences are used to convey information, such as required form fields, the information conveyed by the color differences are also conveyed explicitly in text.

The objective of this technique is to avoid flashing at rates that are known to cause seizures if the flashes are bright and large enough. Since some users may be using screen enlargers, this technique limits the flashing of any size content to no more than three flashes in any 1-second period.

The objective of this technique is to provide a logical tab order when the default tab order does not suffice. Often, G59: Placing the interactive elements in an order that follows sequences and relationships within the content is sufficient and this technique is not necessary. It can be very easy to introduce usability bugs when setting the tab order explicitly.

The objective of this technique is to describe the purpose of a link by providing deive text as the content of the a element. The deion lets a user distinguish this link from other links in the Web page and helps the user determine whether to follow the link. The URI of the destination is generally not sufficiently deive. When an image is the only content of a link, the text alternative for the image describes the unique function of the link. When the content of a link contains both text and one or more images, if the text is sufficient to describe the purpose of the link, the images may have an empty text alternative. (See Using null alt text and no title attribute on img elements for images that assistive technology should ignore.) When the images convey information beyond the purpose of the link, they must also have appropriate alt text.

The objective of this technique is to demonstrate how to use a title attribute on an anchor element to provide additional text describing a link. The title attribute is used to provide additional information to help clarify or further describe the purpose of a link. If the supplementary information provided through the title attribute is something the user should know before following the link, such as a warning, then it should be provided in the link text rather than in the title attribute.

The objective of this technique is to provide text alternatives that serve the same purpose as the selectable regions of an image map. An image map is an image divided into selectable regions defined by area elements. Each area is a link to another Web page or another part of the current Web page. The alt attribute of each area element serves the same purpose as the selectable area of the image.

The objective of this technique is to identify the purpose of a link from the link in its data table context. This context is the table cell enclosing the link and the cell's associated table header cells. The data table context provides the purpose for an otherwise unclear link when the table cell is the nearest enclosing block-level ancestor element. It lets a user distinguish this link from other links in the Web page that lead to other destinations and helps the user determine whether to follow the link. Note that simply providing the URI of the destination is not sufficiently deive for people with disabilities, especially those with cognitive disabilities.

The objective of this technique is to notify the user when a field that must be completed has not been completed. When users fail to provide input for any mandatory form fields, information is provided in text to enable the users to identify which fields were omitted. One approach is to use client-side validation and provide an dialog box identifying the mandatory fields which were omitted. Another approach, using server-side validation, is to re-display the form (including any previously entered data), with either a text deion at the location of the omitted mandatory field, or a text deion that identifies the omitted mandatory fields.

The objective of this technique is to validate user input as values are entered for each field, by means of client-side ing. If errors are found, an dialog describes the nature of the error in text. Once the user dismisses the dialog, it is helpful if the positions the keyboard focus on the field where the error occurred.

The objective of this technique is to avoid ambiguities in Web pages that often result from code that does not validate against formal specifications. Each technology's mechanism to specify the technology and technology version is used, and the Web page is validated against the formal specification of that technology. If a validator for that technology is available, the developer can use it.

The objective of this technique is to use HTML and XHTML heading markup to convey the structure of the content.

The objective of this technique is to use the label element to explicitly associate a form control with a label. A label is attached to a specific form control through the use of the for attribute. The value of the for attribute must be the same as the value of the id attribute of the form control.

The objective of this technique is to group navigation links using the HTML5 nav element. The nav element is one of several sectioning elements in HTML5. Use of this markup can make groups of links easier to locate and skip past by users of assistive technology such as screen readers. Using semantic structures allow custom style sheets to be used to change the presentation of groups of links while preserving their relationship. When the nav element is employed more than once on a page, distinguish the navigation groups by using an aria-label or aria-labelledby attribute.

The objective of this technique is to programmatically associate captions for data tables where captions are provided in the presentation. The caption for a table is a table identifier and acts like a title or heading for the table.

The objective of this technique is to associate each data cell (in a data table) with the appropriate headers. This technique adds a headers attribute to each data cell (td element). It also adds an id attribute to any cell used as a header for other cells. The headers attribute of a cell contains a list of the id attributes of the associated header cells. If there is more than one id, they are separated by spaces.

The objective of this technique is to present tabular information in a way that preserves relationships within the information even when users cannot see the table or the presentation format is changed. Information is considered tabular when logical relationships among text, numbers, images, or other data exist in two dimensions (vertical and horizontal). These relationships are represented in columns and rows, and the columns and rows must be recognizable in order for the logical relationships to be perceived.

The objective of this technique is to associate header cells with data cells using the scope attribute. The scope attribute may be used to clarify the scope of any cell used as a header. The scope identifies whether the cell is a header for a row, column, or group of rows or columns. The values row, col, rowgroup, and colgroup identify these possible scopes respectively.

The objective of this technique is to use the title attribute to label form controls when the visual design cannot accommodate the label (for example, if there is no text on the screen that can be identified as a label) or where it might be confusing to display a label. User agents, including assistive technology, can speak the title attribute.

The objective of this technique is to provide a brief overview of how data has been organized into a table or a brief explanation of how to navigate the table. The summary attribute of the table element makes this information available to people who use screen readers; the information is not displayed visually.

The objective of this technique is to group items in a selection list. A selection list is a set of allowed values for a form control such as a multi-select list or a combo box. Often, selection lists have groups of related options. Those groups should be semantically identified, rather than simply delimiting the groups with "dummy" list entries. This allows user agents to collapse the options by group to support quicker skimming of the options, and to indicate in what group an option of interest is located. It also helps to visually break up long lists so that users can more easily locate the option(s) they are interested in.

The objective of this technique is to identify the default language of a document by providing the lang and/or xml:lang attribute on the html element.

The objective of this technique is to provide a mechanism that allows users to explicitly request changes of context. The intended use of a submit button is to generate an HTTP request that submits data entered in a form, so it is an appropriate control to use for causing a change of context.

The objective of this technique is to allow the user to control when an action is performed, rather than having the action occur as a side effect of choosing a value for the select element. The user may inspect the different values of the select element, or may accidentally choose the wrong value, without causing the action to occur. When the user is satisfied with their choice, they select the button to perform the action.

The objective of this technique is to use the label element to explicitly associate a form control with a label. A label is attached to a specific form control through the use of the for attribute. The value of the for attribute must be the same as the value of the id attribute of the form control.

The objective of this technique is to help the user avoid input errors by informing them about restrictions on the format of data that they must enter. This can be done by describing characteristics of the format or providing a sample of the format the data should have.

The objective of this technique is to use the title attribute to label form controls when the visual design cannot accommodate the label (for example, if there is no text on the screen that can be identified as a label) or where it might be confusing to display a label. User agents, including assistive technology, can speak the title attribute.

The objective of this technique is to use the label element to explicitly associate a form control with a label. A label is attached to a specific form control through the use of the for attribute. The value of the for attribute must be the same as the value of the id attribute of the form control.

The objective of this technique is to demonstrate the use of the title attribute of the frame or iframe element to describe the contents of each frame. This provides a label for the frame so users can determine which frame to enter and explore in detail. It does not label the individual page (frame) or inline frame (iframe) in the frameset. Note that the title attribute labels frames, and is different from the title element which labels documents. Both should be provided, since the first facilitates navigation among frames and the second clarifies the user's current The title attribute is not interchangeable with the name attribute. The title labels the frame for users; the name labels it for ing and window targeting. The name is not presented to the user, only the title is.

The objective of this technique is to use the title attribute to label form controls when the visual design cannot accommodate the label (for example, if there is no text on the screen that can be identified as a label) or where it might be confusing to display a label. User agents, including assistive technology, can speak the title attribute.

For all user interface components (including but not limited to: form elements, links and components generated by s), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies.

The purpose of this technique is to provide an accessible alternative way of presenting the information in an audio-only presentation.

The purpose of this technique is to provide an accessible alternative way of presenting the information in an video-only presentation.

The objective of this technique is to use the HTML5 track element to specify a deions timed text track for a video element. Audio deion timed text tracks contain textual deions of the video component of the media resource, intended for audio synthesis when the visual component is obscured, unavailable, or not usable. The user agent makes the cues available to the user in a non-visual fashion, for instance, by synthesizing them into speech.

The objective of this technique is to provide a way for people who have hearing impairments or otherwise have trouble hearing the dialog in synchronized media material to be able to view the material and see the dialog and sounds - without requiring people who are not deaf to watch the captions. With this technique all of the dialog and important sounds are embedded as text in a fashion that causes the text not to be visible unless the user requests it. As a result they are visible only when needed. This requires special support for captioning in the user agent.

The objective of this technique is to use the HTML5 track element to specify a captions timed text track for a video element. Caption timed text tracks contain tranion or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information, suitable for when sound is unavailable or not clearly audible.

The purpose of this technique is to provide an accessible alternative way of presenting the information in a synchronized media presentation.

The objective of this technique is to provide an audio (spoken) version of information that is provided visually so that it is possible for people who cannot see to be able to understand audio-visual material better.

The objective of this technique is to all additional audio deion to be inserted into a synchronized media presentation when there is not enough time in the gaps int the dialog. This is done by simply freezing the image so that additional audio deion of the video can be played. When the deion is finished, the synchronized media continues.

The objective of this technique is to provide a text alternative for content rendered using the object element. The body of the object element can be used to provide a complete text alternative for the object or may contain additional non-text content with text alternatives.

The objective of this technique is to identify changes in the text direction of text that includes nested directional runs by providing the dir attribute on inline elements. A nested directional run is a run of text that includes mixed directional text, for example, a paragraph in English containing a quoted Hebrew sentence which in turn includes an English phrase. Use of the dir attribute on an enclosing span or other inline element may be necessary because the Unicode bidirectional algorithm can produce undesirable results when mixed directional text contains spaces or punctuation. The concepts used in this technique are described in What you need to know about the bidi algorithm and inline markup.

The purpose of this technique is to allow authors to play a sound on their Web page but avoid the problem of users not being able to use their screen readers due to interference by the content sound. It also allows the author to avoid putting controls on the Web page to control the sound - and the problem faced by users with screen readers in finding the control (when unable to hear their screen reader).

When content includes multiple formats, one or more user agents or plug-ins are often needed in order to successfully present the content to users. For example, a page that includes XHTML, SVG, SMIL and XForms may require a browser to load as many as three different plug-ins in order for a user to successfully interact with the content. Some plug-ins create a common situation in which the keyboard focus can become "stuck" in a plug-in, leaving a keyboard-only user with no way to return to the other content.

The objective of this technique is to allow user to extend the default time limit by providing a mechanism to extend the time when s provide functionality that has default time limits. In order to allow the user to request a longer than default time limit, the can provide a form (for example) allowing the user to enter a larger default time limit. Making this available as a preference setting allows users to indicate their requirements in advance. If warning the user a time limit is about to expire (see SCR16: Providing a that warns the user a time limit is about to expire (Scripting) ), this form can be made available from the warning dialog.

CSS defines the blink value for the text-decoration property. When used, it causes any text in elements with this property to blink at a predetermined rate. This cannot be interrupted by the user, nor can it be disabled as a user agent preference. The blinking continues as long as the page is displayed. Therefore, content that uses text-decoration:blink fails the Success Criterion because blinking can continue for more than three seconds.

The objective of this technique is to demonstrate the use of the title attribute of the frame or iframe element to describe the contents of each frame. This provides a label for the frame so users can determine which frame to enter and explore in detail. It does not label the individual page (frame) or inline frame (iframe) in the frameset. Note that the title attribute labels frames, and is different from the title element which labels documents. Both should be provided, since the first facilitates navigation among frames and the second clarifies the user's current The title attribute is not interchangeable with the name attribute. The title labels the frame for users; the name labels it for ing and window targeting. The name is not presented to the user, only the title is.

The objective of this technique is to provide a method for activating things that is predictable by the user. Users with cognitive disabilities and people using screen readers or screen magnifiers may be confused by an unexpected event such as automatic form submission or activation of a function that causes a change of context.

The objective of this technique is to make sure that users can read text that is presented over a background. This technique relaxes the 5:1 contrast ratio requirement for text that is at least 18 point (if not bold) or at least 14 point (if bold).

The objective of this technique is to make sure that users can read text that is presented over a background. For Success Criterion 1.4.3, this technique describes the minimum contrast ratio for text that is less than 18 point (if not bold) and less than 14 point (if bold). For Success Criterion 1.4.5, this technique relaxes the 7:1 contrast ratio requirement for text that is at least 18 point (if not bold) or at least 14 point (if bold). If the background is a solid color (or all black or all white) then the relative luminance of the text can be maintained by making sure that each of the text letters have 4.5:1 contrast ratio with the background. If the background or the letters vary in relative luminance (or are patterned) then the background around the letters can be chosen or shaded so that the letters maintain a 4.5:1 contrast ratio with the background behind them even if they do not have that contrast ratio with the entire background. The contrast ratio can sometimes be maintained by changing the relative luminance of the letters as the relative luminance of the background changes across the page. Another method is to provide a halo around the text that provides the necessary contrast ratio if the background image or color would not normally be sufficiently different in relative luminance.

Users with vision loss or cognitive challenges often require specific foreground (text) and background color combinations. For instance, many people with low vision find it much easier to see a Web page that has white text on a black background, so they may have set their user agent to create this contrast. If the author specifies that the text must be black, then it may override the settings of the user agent and render a page that has black text (specified by the author) on black background (that was set in the user agent). This principle also works in reverse. If the Webmaster forces the background to be white, then the white background specified by the author would be the same color as the white text (which was set in the user agent) rendering the page unusable to the user. Therefore, if the author specifies a foreground (text) color then they should also specify a background color which has sufficient contrast (link) with the foreground and vice versa.

If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text

The objective of this technique is to demonstrate how CSS can be used to replace structured HTML text with images of text in a way that makes it possible for users to view content according to their preferences. To use this technique, an author starts by creating an HTML page that uses semantic elements to mark up the structure of the page. The author then designs two or more stylesheets for that page. One stylesheet presents the HTML text as text and the second uses CSS features to replace some of the HTML text with images of text. Finally, through the use of server-side or client-side ing, the author provides a control that allows the user to switch between the available views.

The objective of this technique is to make section headings within Web content deive. Deive headings and titles (see G88: Providing deive titles for Web pages) work together to give users an overview of the content and its organization. Deive headings identify sections of the content in relation both to the Web page as a whole and to other sections of the same Web page.

The objective of this technique is to ensure that the focused component can be visually identified by the user by relying on user agent support. It is common for user agents to highlight standard controls in some way when they receive focus. UAAG-conformant user agents do so when they satisfy checkpoint 10.2 "Highlight selection, content focus, enabled elements, visited links". When authors use standard controls for which the user agent provides this support, users are informed of the focus location in a standard, predictable way.

The objective of this technique is to clearly identify any changes in language on a page by using the lang or xml:lang attribute, as appropriate for the HTML or XHTML version you use.

This describes a failure condition for all techniques involving navigation mechanisms that are repeated on multiple Web pages within a set of Web pages (Success Criterion 3.2.3). If the mechanism presents the order of links in a different order on two or more pages, then the failure is triggered.

The purpose of this technique is to help for users with cognitive disabilities, blindness and vision loss to understand what will happen when they interact with a function on a Web page. If there are different labels on user interface components (i.e., elements, links, JavaScript objects, etc.) that have the same function, the user will not know that they have encountered a component with the same function and will not know what to expect. This could lead to many unnecessary errors. It is also recommended that this approach to consistent labelling be applied across the Web site.

The objective of this technique is to validate user input as values are entered for each field, by means of client-side ing. If errors are found, an dialog describes the nature of the error in text. Once the user dismisses the dialog, it is helpful if the positions the keyboard focus on the field where the error occurred.

The objective of this technique is to provide users with a way to ensure their input is correct before completing an irreversible transaction. Testing, financial, and legal applications permit transactions to occur which cannot be "undone". It is therefore important that there be no errors in the data submission, as the user will not have the opportunity to correct the error once the transaction has been committed.

The objective of this technique is to validate user input as values are entered for each field, by means of client-side ing. If errors are found, an dialog describes the nature of the error in text. Once the user dismisses the dialog, it is helpful if the positions the keyboard focus on the field where the error occurred.

The objective of this technique is to specify text font size proportionally so that user agents can scale content effectively. If a font-size is specified for the body element, all other elements inherit that value, unless overridden by a more specific selector.

The objective of this technique is to ensure text-based form controls resize when text size is changed in the user agent. This will allow users to enter text and read what they have entered in input boxes because the text is displayed at the size required by the user.Text-based form controls include input boxes (text and textarea) as well as buttons.

The objective of this technique is to allow users who cannot hear to be able to access real-time synchronized media broadcasts. It is more difficult to create accurate real-time captions because there is little time to correct mistakes or to listen a second time or consult someone to be sure the words are accurately reproduced. It is also harder to simplify or paraphrase information if it is flowing too quickly.

The objective of this technique is to provide an audio (spoken) version of information that is provided visually so that it is possible for people who cannot see to be able to understand audio-visual material better.

The objective of this technique is to all additional audio deion to be inserted into a synchronized media presentation when there is not enough time in the gaps int the dialog. This is done by simply freezing the image so that additional audio deion of the video can be played. When the deion is finished, the synchronized media continues.

The objective of this technique is to describe how the link element can provide metadata about the position of an HTML page within a set of Web pages or can assist in locating content with a set of Web pages. The value of the rel attributes indicates what type of relation is being described, and the href attribute provides a link to the document having that relation. Multiple link elements can provide multiple relationships. Several values of rel are useful: