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[ WCAG 2.1 解説書 ]
Understanding SC 2.5.3:Label in Name (Level A)
In Brief
- Goal
- The visual label for controls is a trigger for speech activation.
- What to do
- Where practical, make the control’s text label and name match.
- Why it's important
- People who operate with voice interaction use the visible labels in their commands.
Intent
The intent of this Success Criterion is to ensure that the words which visually label a component are also the words associated with the component programmatically. This helps ensure that people with disabilities can rely on visible labels as a means to interact with the components.
Most controls are accompanied by a visible text label. Those same controls have a programmatic name, also known as the Accessible Name. Users typically have a much better experience if the words and characters in the visible label of a control match or are contained within the accessible name. When these match, speech-input users (i.e., users of speech recognition applications) can navigate by speaking the visible text labels of components, such as menus, links, and buttons, that appear on the screen. Sighted users who use text-to-speech (e.g., screen readers) will also have a better experience if the text they hear matches the text they see on the screen.
Note that where a visible text label does not exist for a component, this Success Criterion does not apply to that component.
Where text labels exist and are properly linked to the user interface components through established authoring practices, the label and name will normally match. When they don't match, speech-input users who attempt to use the visible text label as a means of navigation or selection (e.g., "move to Password") will be unsuccessful. The speech-based navigation fails because the visible label spoken by the users does not match (or is not part of) the accessible name that is enabled as a speech-input command. In addition, when the accessible name is different from the visible label, it may function as a hidden command that can be accidentally activated by speech-input users.
Mismatches between visible labels and programmatic names for controls are even more of an issue for speech-input and text-to-speech users who also have cognitive challenges. Mismatches create an extra cognitive load for speech-input users, who must remember to say a speech command that is different from the visible label they see on a control. It also creates extra cognitive load for a text-to-speech user to absorb and understand speech output that does not match the visible label.
In order for the label text and accessible name to be matched, it is first necessary to determine which text on the screen should be considered a label for any given control. There are often multiple text strings in a user interface that may be relevant to a control. However, there are reasons why it is best to conservatively interpret the label as being only the text in close proximity.
Conventionally the label for user interface components is the adjacent text string. The typical positioning for left to right languages is:
- immediately to the left of comboboxes, dropdown lists, text inputs, and other widgets (or in the absence of left-side labels, immediately above and aligned with the left edge of each input)
- immediately to the right of checkboxes and radio buttons
- inside buttons and tabs or immediately below icons serving as buttons
The rationale for some of these conventions is explained in G162: Positioning labels to maximize predictability of relationships.
It is important to bias towards treating only the adjacent text as a label because liberal interpretations of what constitutes a text label can jeopardize the value of this Success Criterion (SC) by lessening predictability. Isolating the label to the single string in close proximity to the component makes it easier for developers, testers, and end users to identify the label targeted for evaluation in this SC. Predictable interpretation of labeling allows users of speech recognition technologies to interact with the element via its conventionally positioned label, and allows users of screen reading technologies to enjoy consistency between the nearby visible label and the announced name of the component.
Note that placeholder text within an input field is not considered an appropriate
means of providing a label. The HTML5 specification states The placeholder attribute should not be used as an alternative to a <label>.
However, it is worth noting that "label" in that HTML5 statement is in code brackets
and links to the label
element. For the purposes of this Label in Name Success Criterion, "label" is not
used in such a programmatic sense but is simply referring to a text string in close
visual proximity to a component. As such, in the absence of any other nearby text
string (as described in the preceding list), if an input contains placeholder text,
such text may be a candidate for Label in Name. This is supported both through the
accessible name calculation (discussed later) and from the practical sense that where
a visible label is not otherwise provided, it is likely that a speech-input user may
attempt to use the placeholder text value as a means of interacting with the input.
Text labels "express something in human language"
Symbolic text characters
For the purposes of this SC, text should not be considered a visible label if it is
used in a symbolic manner, rather than directly expressing something in human language
as per the definition of text in WCAG. For example, 1.4.5 Images of Text describes considerations for "symbolic text characters." In the images of text example
"B", "I", and "ABC" appear on icons in a text editor, where they are meant to symbolize
the functions for Bold, Italics, and Spelling, respectively. In such a case, the accessible
name should be the function the button serves (e.g., "Spell check" or "Check spelling"),
not the visible symbolic characters. A similar text editor is shown in the figure
below.
Likewise, where an author has used a greater-than symbol (">") to mimic the appearance of the right-facing arrow, the text does not convey something in human language. It is a symbol, in this scenario likely meant to mimic the icons used for a "Play" button or a "Next" arrow.
Punctuation and capitalization
The use of punctuation and capitalization in labels may also be considered optional for the same reason. For example, the colon conventionally added at the end of input labels does not express something in human language, and capitals on the first letter of each word in a label do not normally alter the words' meaning. This is particularly relevant in the context of this SC, since it is primarily aimed at users of speech recognition; capitals and most punctuation are frequently ignored when a user speaks a label as a means of interacting with a control.
While it is certainly not an error to include the colon and capitalization in the
accessible name, a computed name of "First name" should not be considered a failure
of "First Name:".
Likewise, "Next…" visibly shown on a button could have "Next" as the accessible name.
When in doubt, where a meaningful visible label exists, match the string exactly for
the accessible name.
Mathematical expressions and formulae
Mathematical expressions are an exception to the previous subsection about symbolic
characters. Math symbols can be used as labels; for example "11×3=33" and "A>B" convey
meaning. The label should not be overwritten in the accessible name, and substitutions
of words where a formula is used should be avoided since there are multiple ways to
express the same equation. For example, making the name "eleven multiplied by three
is equivalent to thirty-three" might mean a user who said "eleven times three equals
thirty-three" may not match. It is best to leave the formulas as used in the label
and count on the user's familiarity with their speech software to achieve a match.
Further, converting a mathematical formula label into an accessible name that is a
spelled-out equivalent may create issues for translation. The name should match the
label's formula text. Note that a consideration for authors is to use the proper symbol
in the formula. For instance 11x3 (with a lower or upper case letter X), 11*3 (with
the asterisk symbol), and 11×3 (with the &
times;
symbol) are all easy for sighted users to interpret as meaning the same formula,
but may not all be matched to "11 times 3" by the speech recognition software. The
proper operator symbol (in this case the times symbol) should be used.
Accessible Name and Description Computation specification
It is important to understand how the accessible name is derived. The Accessible Name and Description Computation 1.1 and the HTML Accessibility API Mappings 1.0 describe how the accessible name is computed, including which attributes are considered in its calculation, and in what order of preference. If a component has multiple possible attribute values that could be used for its accessible name, only the most preferred of those values will be computed. None of the other, less preferred values will be part of the name. For the most part, existing established programmatic relationships between labels and controls are reinforced by the specification.
Other text displayed on the screen that is correctly coded to meet 1.3.1: Info and Relationships is not normally factored into the calculation for the accessible name of a UI component without author intervention (via ARIA labeling techniques). The most common of these are:
- headings and instructions
- group labels for sets of components (i.e., used with
legend
/fieldset
or with role ofgroup
orradiogroup
)
Such textual information may constitute part of the component's description. So from both a programmatic viewpoint, and from the conservative tactic of only considering a label to be "adjacent text," neither headings, instructions, nor group 'labels' should normally be considered labels for the purpose of this Success Criterion.
It is important to note that the specification allows authors to override the name
calculated through native semantics. Both aria-label
and aria-labelledby
take precedence in the name calculation, overriding the visible text as the accessible
name even when the visible text label is programmatically associated with the control.
For this reason, when a visible label already exists, aria-label
should be avoided or used carefully, and aria-labelledby
should be used as a supplement with care.
Finally, aria-describedby
is not included in the Accessible Name computation (instead it is part of the Accessible
Description computation). By convention, text associated with a control through aria-describedby
is announced immediately after the accessible name by screen readers. Therefore,
the context of headings, instructions, and group labels can be provided through the
accessible description to assist users of screen readers without affecting the experience
of those who navigate using speech recognition software.
Benefits
- Speech-input users can directly activate controls on a page with fewer surprising changes of focus.
- Text-to-speech users will have a better experience because the labels that they hear match the visible text labels that they see on the screen.
Examples
- Accessible name matches visible label: The accessible name and visible label of a control match.
- Accessible name starts with visible label: The accessible name "Search for a value" begins with the text of the visible label, "Search".
Related Resources
Resources are for information purposes only, no endorsement implied.
Techniques
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. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.
Sufficient Techniques
Advisory Techniques
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.
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.
- G162: Positioning labels to maximize predictability of relationships
- If an icon has no accompanying text, consider using its hover text as its accessible name (Potential future technique)
Failures
The following are common mistakes that are considered failures of this Success Criterion by the WCAG Working Group.
- F96: Failure due to the accessible name not containing the visible label text
- Accessible name contains the visible label text, but the words of the visible label are not in the same order as they are in the visible label text (Potential future technique)
- Accessible name contains the visible label text, but one or more other words are interspersed in the label (Potential future technique)
Key Terms
picture created by a spatial arrangement of characters or glyphs (typically from the 95 printable characters defined by ASCII)
hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents
Note
Functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).
Note
Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.
Note
The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving Web content from program objects or parsing markup into identifiable bundles.
information and sensory experience to be communicated to the user by means of a user agent, including code or markup that defines the content's structure, presentation, and interactions
language that is spoken, written or signed (through visual or tactile means) to communicate with humans
Note
See also sign language.
text that has been rendered in a non-text form (e.g., an image) in order to achieve a particular visual effect
Note
This does not include text that is part of a picture that contains significant other visual content.
text or other component with a text alternative that is presented to a user to identify a component within Web content
Note
A label is presented to all users whereas the name may be hidden and only exposed by assistive technology. In many (but not all) cases the name and the label are the same.
Note
The term label is not limited to the label element in HTML.
text by which software can identify a component within Web content to the user
Note
The name may be hidden and only exposed by assistive technology, whereas a label is presented to all users. In many (but not all) cases, the label and the name are the same.
Note
This is unrelated to the name attribute in HTML.
any content that is not a sequence of characters that can be programmatically determined or where the sequence is not expressing something in human language
Note
This includes ASCII Art (which is a pattern of characters), emoticons, leetspeak (which uses character substitution), and images representing text
rendering of the content in a form to be perceived by users
determined by software from author-supplied data provided in a way that different user agents, including assistive technologies, can extract and present this information to users in different modalities
a language using combinations of movements of the hands and arms, facial expressions, or body positions to convey meaning
sequence of characters that can be programmatically determined, where the sequence is expressing something in human language
Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. Programmatically associated text is text whose location can be programmatically determined from the non-text content.
Note
Refer to Understanding Text Alternatives for more information.
any software that retrieves and presents Web content for users
a part of the content that is perceived by users as a single control for a distinct function
Note
Multiple user interface components may be implemented as a single programmatic element. "Components" here is not tied to programming techniques, but rather to what the user perceives as separate controls.
Note
User interface components include form elements and links as well as components generated by scripts.
Note
What is meant by "component" or "user interface component" here is also sometimes called "user interface element".
a non-embedded resource obtained from a single URI using HTTP plus any other resources that are used in the rendering or intended to be rendered together with it by a user agent
Note
Although any "other resources" would be rendered together with the primary resource, they would not necessarily be rendered simultaneously with each other.
Note
For the purposes of conformance with these guidelines, a resource must be "non-embedded" within the scope of conformance to be considered a Web page.
Test Rules
The following are Test Rules for certain aspects of this Success Criterion. It is not necessary to use these particular Test Rules to check for conformance with WCAG, but they are defined and approved test methods. For information on using Test Rules, see Understanding Test Rules for WCAG Success Criteria.