瓜子仁卡在女童气管20余天间断喘息入院治疗
百度 ”英国剑桥大学贾奇商学院(CambridgeJudgeBusinessSchool)戴维·莱纳教授(DavidReiner)说，剑桥建立了专门的项目把不同学院、不同专业的人才集中到一起，使得剑桥的创新成果排名在整个欧洲靠前。2.4.4 Link Purpose (In Context): The purpose of each link can be determined from the link text alone, or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general. (Level A)
Intent of this Success Criterion
The intent of this Success Criterion is to help users understand the purpose of each link so they can decide whether they want to follow the link. Whenever possible, provide link text that identifies the purpose of the link without needing additional context. Assistive technology has the ability to provide users with a list of links that are on the Web page. Link text that is as meaningful as possible will aid users who want to choose from this list of links. Meaningful link text also helps those who wish to tab from link to link. Meaningful links help users choose which links to follow without requiring complicated strategies to understand the page.
In some situations, authors may want to provide part of the description of the link in logically related text that provides the context for the link. In this case the user should be able to identify the purpose of the link without moving focus from the link. In other words, they can arrive on a link and find out more about it without losing their place. This can be achieved by putting the description of the link in the same sentence, paragraph, list item, the heading immediately preceding the link, or table cell as the link, or in the table header cell for a link in a data table, because these are directly associated with the link itself.
This context will be most usable if it precedes the link. (For instance, if you must use ambiguous link text, it is better to put it at the end of the sentence that describes its destination, rather than putting the ambiguous phrase at the beginning of the sentence.) If the description follows the link, there can be confusion and difficulty for screen reader users who are reading through the page in order (top to bottom).
Links with the same destination should have the same descriptions (per Success Criterion 3.2.4 ), but links with different purposes and destinations should have different descriptions.
The Success Criterion includes an exception for links for which the purpose of the link cannot be determined from the information on the Web page. In this situation, the person with the disability is not at a disadvantage; there is no additional context available to understand the link purpose. However, whatever amount of context is available on the Web page that can be used to interpret the purpose of the link must be made available in the link text or programmatically associated with the link to satisfy the Success Criterion.
Note: There may be situations where the purpose of the link is is supposed to be unknown or obscured. For instance, a game may have links identified only as door #1, door #2, and door #3. This link text would be sufficient because the purpose of the links is to create suspense for all users.
Specific Benefits of Success Criterion 2.4.4:
This Success Criterion helps people with motion impairment by letting them skip links that they are not interested in, avoiding the keystrokes needed to visit the referenced content and then returning to the current content.
People with cognitive limitations will not become disoriented by multiple means of navigation to and from content they are not interested in.
People with visual disabilities will be able to determine the purpose of a link by exploring the link's context.
Examples of Success Criterion 2.4.4
A link contains text that gives a description of the information at that URL
A page contains the sentence "There was much bloodshed during the Medieval period of history." Where "Medieval period of history" is a link.
A link is preceded by a text description of the information at that URL
A page contains the sentence "Learn more about the Government of Ireland's Commission on Electronic Voting at Go Vote!" where "Go Vote!" is a link.
Both an icon and text are included in the same link
An icon of a voting machine and the text "Government of Ireland's Commission of Electronic Voting" are combined to make a single link. The alt text for the icon is null, since the purpose of the link is already described by the text of the link next to the icon.
A list of book titles
A list of books is available in three formats: HTML, PDF, and mp3 (a recording of a person reading the book). To avoid hearing the title of each book three times (once for each format), the first link for each book is the title of the book, the second link says "PDF" and the third says, "mp3."
News article summaries
A Web page contains a collection of news articles. The main page lists the first few sentences of each article, followed by a "Read more" link. A screen reader command to read the current paragraph provides the context to interpret the purpose of the link.
Related Resources
Resources are for information purposes only, no endorsement implied.
Techniques and Failures for Success Criterion 2.4.4 - Link Purpose (In Context)
Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. The techniques listed only satisfy the Success Criterion if all of the WCAG 2.0 conformance requirements have been met.
Sufficient Techniques
G91: Providing link text that describes the purpose of a link
Allowing the user to choose short or long link text using one of the technology specific techniques below:
Using HTML and page reloads to offer different link texts (future link)
Using JavaScript to change the link texts (future link)
Providing a supplemental description of the purpose of a link using one of the following techniques:
Identifying the purpose of a link using link text combined with programmatically determined link context using one of the following techniques:
Optimizing Web pages for the "link list" feature in assistive technology (future link)
Additional Techniques (Advisory) for 2.4.4
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Failures for SC 2.4.4
The following are common mistakes that are considered failures of Success Criterion 2.4.4 by the WCAG Working Group.
Key Terms
- ambiguous to users in general
the purpose cannot be determined from the link and all information of the Web page presented to the user simultaneously with the link (i.e. readers without disabilities would not know what a link would do until they activated it)
Example: The word guava in the following sentence "One of the notable exports is guava" is a link. The link could lead to a definition of guava, a chart listing the quantity of guava exported or a photograph of people harvesting guava. Until the link is activated, all readers are unsure and the person with a disability is not at any disadvantage.
- link purpose
nature of the result obtained by activating a hyperlink
- Programmatically determiend (programmatically determinable) link context
additional information that can be programmatically determined from relationships with a link, combined with the link text, and presented to users in different modalities
Example: In HTML, information that is programmatically determinable from a link in English includes text that is in the same paragraph, list, or table cell as the link or in a table header cell that is associated with the table cell that contains the link.
Note: Since screen readers interpret punctuation, they can also provide the context from the current sentence, when the focus is on a link in that sentence.