Criteria for apps

Principle 1 - Perceivable

Information and user interface components must be presentable to users in ways they can perceive.

Guideline 1.1 - Text Alternatives

Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.

1.1.1 Non-text Content (Level A)

All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below.

Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Success Criterion 4.1.2 for additional requirements for controls and content that accepts user input.)

Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)

Test: If non-text content is a test or exercise that would be invalid if presented in text, then text alternatives at least provide descriptive identification of the non-text content.

Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.

CAPTCHA: If the purpose of non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.

Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

Guideline 1.2 - Time-based Media

Provide alternatives for time-based media.

1.2.1 Audio-only and Video-only (Prerecorded) (Level A)

For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such:

Prerecorded Audio-only: An alternative for time-based media is provided that presents equivalent information for prerecorded audio-only content.

Prerecorded Video-only: Either an alternative for time-based media or an audio track is provided that presents equivalent information for prerecorded video-only content.

1.2.2 Captions (Prerecorded) (Level A)

Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such.

1.2.3 Audio Description or Media Alternatives (Prerecorded) (Level A)

An alternative for time-based media or audio description of the prerecorded video content is provided for synchronized media, except when the media is a media alternative for text and is clearly labeled as such.

1.2.5 Audio Description (Prerecorded) (Level AA)

Audio description is provided for all prerecorded video content in synchronized media.

Guideline 1.3 - Adaptable

Create content that can be presented in different ways (for example simpler layout) without losing information or structure.

1.3.1 Info and Relationships (Level A)

Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text.

1.3.2 Meaningful Sequence (Level A)

Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text.

1.3.3 Sensory Characteristics (Level A)

Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, color, size, visual location, orientation, or sound.

Note 1: For requirements related to color, refer to Guideline 1.4.

1.3.4 Orientation (Level AA)

Content does not restrict its view and operation to a single display orientation, such as portrait or landscape, unless a specific display orientation is essential.

1.3.5 Identify Input Purpose (Level AA)

The purpose of each input field collecting information about the user can be programmatically determined when:

The input field serves a purpose identified in the Input Purposes for User Interface Components section; and

The content is implemented using technologies with support for identifying the expected meaning for form input data.

Guideline 1.4 - Distinguishable

Make it easier for users to see and hear content including separating foreground from background.

1.4.1 Use of Color (Level A)

Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

Note 1: This success criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3 including programmatic access to color and other visual presentation coding.

1.4.2 Audio Control (Level A)

If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level.

Note 1: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether or not it is used to meet other success criteria) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

1.4.3 Contrast (Minimum) (Level AA)

The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following:

Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1;

Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.

Logotypes: Text that is part of a logo or brand name has no contrast requirement.

1.4.4 Resize text (Level AA)

Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality.

1.4.5 Images of text (Level AA)

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

Customizable: The image of text can be visually customized to the user's requirements;

Essential: A particular presentation of text is essential to the information being conveyed.

Note 1: Logotypes (text that is part of a logo or brand name) are considered essential.

1.4.10 Reflow (Level AA)

Content can be presented without loss of information or functionality, and without requiring scrolling in two dimensions for:

Vertical scrolling content at a width equivalent to 320 CSS pixels;

Horizontal scrolling content at a height equivalent to 256 CSS pixels;

Except for parts of the content which require two-dimensional layout for usage or meaning.

1.4.11 Non-text Contrast (Level AA)

The visual presentation of the following have a contrast ratio of at least 3:1 against adjacent color(s):

User Interface Components: Visual information required to identify user interface components and states, except for inactive components or where the appearance of the component is determined by the user agent and not modified by the author;

Graphical Objects: Parts of graphics required to understand the content, except when a particular presentation of graphics is essential to the information being conveyed.

1.4.12 Text Spacing (Level AA)

In content implemented using markup languages that support the following text style properties, no loss of content or functionality occurs by setting all of the following and by changing no other style property:

Line height (line spacing) to at least 1.5 times the font size;

Spacing following paragraphs to at least 2 times the font size;

Letter spacing (tracking) to at least 0.12 times the font size;

Word spacing to at least 0.16 times the font size.

Exception: Human languages and scripts that do not make use of one or more of these text style properties in written text can conform using only the properties that exist for that combination of language and script.

1.4.13 Content on Hover or Focus (Level AA)

Where receiving and then removing pointer hover or keyboard focus triggers additional content to become visible and then hidden, the following are true:

Dismissible: A mechanism is available to dismiss the additional content without moving pointer hover or keyboard focus, unless the additional content communicates an input error or does not obscure or replace other content;

Hoverable: If pointer hover can trigger the additional content, then the pointer can be moved over the additional content without the additional content disappearing;

Persistent: The additional content remains visible until the hover or focus trigger is removed, the user dismisses it, or its information is no longer valid.

Exception: The visual presentation of the additional content is controlled by the user agent and is not modified by the author.

Principle 2 - Operable

User interface components and navigation must be operable.

Guideline 2.1 - Keyboard Accessible

Make all functionality available from a keyboard.

2.1.1 Keyboard (Level A)

All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints.

Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not.

Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

2.1.2 No Keyboard Trap (Level A)

If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away.

Note 1: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

2.1.4 Character Key Shortcuts (Level A)

If a keyboard shortcut is implemented in content using only letter (including upper- and lower-case letters), punctuation, number, or symbol characters, then at least one of the following is true:

Turn off: A mechanism is available to turn the shortcut off;

Remap: A mechanism is available to remap the shortcut to include one or more non-printable keyboard keys (e.g., Ctrl, Alt);

Active only on focus: The keyboard shortcut for a user interface component is only active when that component has focus.

Guideline 2.2 - Enough Time

Provide users enough time to read and use content.

2.2.1 Timing Adjustable (Level A)

For each time limit that is set by the content, at least one of the following is true:

Turn off: The user is allowed to turn off the time limit before encountering it; or

Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or

Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or

Real-time Exception: The time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or

Essential Exception: The time limit is essential and extending it would invalidate the activity; or

20 Hour Exception: The time limit is longer than 20 hours.

2.2.2 Pause, Stop, Hide (Level A)

For moving, blinking, scrolling, or auto-updating information, all of the following are true:

Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and

Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.

Note 1: For requirements related to flickering or flashing content, refer to Guideline 2.3.

Note 2: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

Note 3: Content that is updated periodically by software or that is streamed to the user agent is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so.

Note 4: An animation that occurs as part of a preload phase or similar situation can be considered essential if interaction cannot occur during that phase for all users and if not indicating progress could confuse users or cause them to think that content was frozen or broken.

Guideline 2.3 - Seizures and Physical Reactions

Do not design content in a way that is known to cause seizures or physical reactions.

2.3.1 Three Flashes or Below Threshold (Level A)

Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds.

Note 1: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

Guideline 2.4 - Navigable

Provide ways to help users navigate, find content, and determine where they are.

2.4.3 Focus Order (Level A)

If a Web page can be navigated sequentially and the navigation sequences affect meaning or operation, focusable components receive focus in an order that preserves meaning and operability.

2.4.4 Link Purpose (In Context) (Level A)

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.

2.4.6 Headings and Labels (Level AA)

Headings and labels describe topic or purpose.

2.4.7 Focus Visible (Level AA)

Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible.

Guideline 2.5 - Input Modalities

Make it easier for users to operate functionality through various inputs beyond keyboard.

2.5.1 Pointer Gestures (Level A)

All functionality that uses multipoint or path-based gestures for operation can be operated with a single pointer without a path-based gesture, unless a multipoint or path-based gesture is essential.

2.5.2 Pointer Cancellation (Level A)

For functionality that can be operated using a single pointer, at least one of the following is true:

No Down-Event: The down-event of the pointer is not used to execute any part of the function;

Abort or Undo: Completion of the function is on the up-event, and a mechanism is available to abort the function before completion or to undo the function after completion;

Up Reversal: The up-event reverses any outcome of the preceding down-event;

Essential: Completing the function on the down-event is essential.

2.5.3 Label in Name (Level A)

For user interface components with labels that include text or images of text, the name contains the text that is presented visually.

2.5.4 Motion Actuation (Level A)

Functionality that can be operated by device motion or user motion can also be operated by user interface components and responding to the motion can be disabled to prevent accidental actuation, except when:

Supported Interface
The motion is used to operate functionality through an accessibility supported interface;

Essential
The motion is essential for the function and doing so would invalidate the activity.

Principle 3 - Understandable

Information and the operation of the user interface must be understandable.

Guideline 3.1- Readable

Make text content readable and understandable.

3.1.1 Language of Page (Level A)

The default human language of each Web page can be programmatically determined.

Guideline 3.2- Predictable

Make Web pages appear and operate in predictable ways.

3.2.1 On Focus (Level A)

When any user interface component receives focus, it does not initiate a change of context.

3.2.2 On Input (Level A)

Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component.

Guideline 3.3- Input Assistance

Help users avoid and correct mistakes.

3.3.1 Error Identification (Level A)

If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text.

3.3.2 Labels of Instructions (Level A)

Labels or instructions are provided when content requires user input.

3.3.3 Error Suggestion (Level AA)

If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content.

3.3.4 Error Prevention (Legal, Financial, Data) (Level AA)

For Web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses, at least one of the following is true:

Reversible: Submissions are reversible.

Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.

Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.

Principle 4 - Robust

Content must be robust enough that it can be interpreted by a wide variety of user agents, including assistive technologies.

Guideline 4.1 - Compatible

Maximize compatibility with current and future user agents, including assistive technologies.

4.1.1 Parsing (Level A)

In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features.

Note 1: This criterion should be considered as always satisfied for any content using HTML or XML.

Note 2: Since this criterion was written, the HTML Standard has adopted specific requirements governing how user agents must handle incomplete tags, incorrect element nesting, duplicate attributes, and non-unique IDs.
Although the HTML Standard treats some of these cases as non-conforming for authors, it is considered to "allow these features" for the purposes of this Success Criterion because the specification requires that user agents support handling these cases consistently. In practice, this criterion no longer provides any benefit to people with disabilities in itself.
Issues such as missing roles due to inappropriately nested elements or incorrect states or names due to a duplicate ID are covered by different Success Criteria and should be reported under those criteria rather than as issues with 4.1.1.

4.1.2 Name, Role, Value (Level A)

For all user interface components (including but not limited to: form elements, links and components generated by scripts), 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.

Note 1: This success criterion is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this success criterion when used according to specification.

4.1.3 Status Messages (Level AA)

In content implemented using markup languages, status messages can be programmatically determined through role or properties such that they can be presented to the user by assistive technologies without receiving focus.

5.2 Activation of accessibility features

Condition: Where web content or ICT has documented accessibility features.

Where ICT has documented accessibility features, it shall be possible to activate those documented accessibility features that are required to meet a specific need without relying on a method that does not support that need.

5.3 Biometrics

Condition: Where web content or ICT uses biological characteristics.

Where ICT uses biological characteristics, it shall not rely on the use of a particular biological characteristic as the only means of user identification or for control of ICT

Note: Alternative means of user identification or for control of ICT could be non-biometric or biometric.

Note: Biometric methods based on dissimilar biological characteristics increase the likelihood that individuals with disabilities possess at least one of the specified biological characteristics. Examples of dissimilar biological characteristics are fingerprints, eye retinal patterns, voice, and face.

5.4 Preservation of accessibility information during conversion

Condition: Where web content or ICT converts information or communication

Where ICT converts information or communication it shall preserve all documented non-proprietary information that is provided for accessibility, to the extent that such information can be contained in or supported by the destination format.

5.5.1 Means of operation

Condition: Only for mobile applications: Where ICT has operable parts

Where ICT has operable parts that require grasping, pinching, or twisting of the wrist to operate, an accessible alternative means of operation that does not require these actions shall be provided.

5.5.2 Operable parts discernibility

Condition: Only for mobile applications: Where ICT has operable parts

Where ICT has operable parts, it shall provide a means to discern each operable part, without requiring vision and without performing the action associated with the operable part.

Note: One way of meeting this requirement is by making the operable parts tactilely discernible.

5.6.1 Tactile or auditory status

Condition: Only for mobile applications: Where ICT has a locking or toggle control

Where ICT has a locking or toggle control and the status of that control is visually presented to the user, the ICT shall provide at least one mode of operation where the status of the control can be determined either through touch or sound without operating the control.

Note: Locking or toggle controls are those controls that can only have two or three states and that keep their state while being used.

Note: An example of a locking or toggle control is the "Caps Lock" key found on most keyboards. Another example is the volume button on a pay telephone, which can be set at normal, loud, or extra loud volume.

5.6.2 Visual status

Condition: Only for mobile applications: Where ICT has a locking or toggle control

Where ICT has a locking or toggle control and the status of the control is non-visually presented to the user, the ICT shall provide at least one mode of operation where the status of the control can be visually determined when the control is presented.

Note: Locking or toggle controls are those controls that can only have two or three states and that keep their state while being used.

Note: An example of a locking or toggle control is the "Caps Lock" key found on most keyboards. An example of making the status of a control determinable is a visual status indicator on a keyboard.

5.7 Key repeat

Condition: Only for mobile applications: Where ICT has a key repeat function that cannot be turned off

Where ICT has a key repeat function that cannot be turned off:

the delay before the key repeat shall be adjustable to at least 2 seconds; and
the key repeat rate shall be adjustable down to one character per 2 seconds.

5.8 Double-strike key acceptance

Condition: Only for mobile applications: Where ICT has a keyboard or keypad

Where ICT has a keyboard or keypad, the delay after any keystroke, during which an additional key-press will not be accepted if it is identical to the previous keystroke, shall be adjustable up to at least 0,5 seconds.

5.9 Simultaneous user actions

Condition: Only for mobile applications: Where ICT uses simultaneous user actions for its operation

Where ICT has a mode of operation requiring simultaneous user actions for its operation, such ICT shall provide at least one mode of operation that does not require simultaneous user actions to operate the ICT.

Note: Having to use both hands to open the lid of a laptop, having to press two or more keys at the same time or having to touch a surface with more than one finger are examples of simultaneous user actions

6.1 Audio bandwidth for speech

Condition: Where web pages or ICT provide two-way voice communication

Where ICT provides two-way voice communication, in order to provide good audio quality, that ICT shall be able to encode and decode two-way voice communication with a frequency range with an upper limit of at least 7 000 Hz.

Note: For the purposes of interoperability, support of Recommendation ITU-T G.722 is widely used.

Note: Where codec negotiation is implemented, other standardized codecs such as Recommendation ITU-T G.722.2 are sometimes used so as to avoid transcoding.

6.2.1.1 RTT communication

Condition: Where web pages or ICT provide a means for two-way voice communication

Where ICT is in a mode that provides a means for two-way voice communication, the ICT shall provide a means for two-way RTT communication, except where this would require design changes to add input or output hardware to the ICT.

Note: This requirement includes those products which do not have physical display or text entry capabilities but have the capability to connect to devices that do have such capabilities. It also includes intermediate ICT between the endpoints of the communication.

Note: There is no requirement to add: a hardware display, a hardware keyboard, or hardware to support the ability to connect to a display or keyboard, wired or wirelessly, if this hardware would not normally be provided.

Note: For the purposes of interoperability, support of Recommendation ITU-T T.140 is widely used.

6.2.1.2 Concurrent voice and text

Condition: Where web pages or ICT provide a means for two-way voice communication and for users to communicate by RTT

Where ICT provides a means for two-way voice communication and for users to communicate by RTT, it shall allow concurrent voice and text through a single user connection.

Note: With many-party communication, as in a conference system, it is allowed (but not required or necessarily recommended) that RTT be handled in a single display field and that "turn-taking" be necessary to avoid confusion (in the same way that turn-taking is required for those presenting/talking with voice).

Note: With many-party communication, best practice is for hand-raising for voice users and RTT users to be handled in the same way, so that voice and RTT users are in the same queue.

Note: With a many-party conference system that has chat as one of its features - the RTT (like the voice) would typically be separate from the chat so that RTT use does not interfere with chat (i.e. people can be messaging in the chat field while the person is presenting/talking with RTT - in the same manner that people message using the chat feature while people are talking with voice). RTT users would then use RTT for presenting and use the Chat feature to message while others are presenting (via Voice or RTT).

Note: The availability of voice and RTT running concurrently (and separately from chat) can also allow the RTT field to support text captioning when someone is speaking (and it is therefore not being used for RTT since it is not the RTT user's turn to speak).

Note: Where both server-side software and local hardware and software are required to provide voice communication, where neither part can support voice communication without the other and are sold as a unit for the voice communication function, the local and server-side components are considered a single product.

6.2.2.1 Visually distinguishable display

Condition: Where web pages or ICT have RTT send and receive capabilities

Where ICT has RTT send and receive capabilities, displayed sent text shall be visually differentiated from, and separated from, received text.

Note: The ability of the user to choose between having the send and receive text be displayed in-line or separately, and with options to select, allows users to display RTT in a form that works best for them. This would allow Braille users to use a single field and take turns and have text appear in the sequential way that they may need or prefer.

6.2.2.2 Programmatically determinable send and receive direction

Condition: Where web pages or ICT have RTT send and receive capabilities

Where ICT has RTT send and receive capabilities, the send/receive direction of transmitted/received text shall be programmatically determinable, unless the RTT is implemented as closed functionality.

Note: This enables screen readers to distinguish between incoming text and outgoing text when used with RTT functionality.

6.2.2.3 Speaker identification

Condition: Where web pages or ICT have RTT capabilities, and provide speaker identification for voice

Where ICT has RTT capabilities, and provides speaker identification for voice, the ICT shall provide speaker identification for RTT.

Note: This is necessary to enable both voice and RTT participants to know who is currently communicating, whether it be in RTT or voice.

6.2.2.4 Visual indicator of audio with RTT

Condition: Where web pages or ICT provide two-way voice communication, and have RTT capabilities

Where ICT provides two-way voice communication, and has RTT capabilities, the ICT shall provide a real-time visual indicator of audio activity on the display.

Note: The visual indicator may be a simple character position on the display that flickers on and off to reflect audio activity, or presentation of the information in another way that can be both visible to sighted users and passed on to deaf-blind users who are using a braille display.

Note: Without this indication a person who lacks the ability to hear does not know when someone is talking.

6.2.3 Interoperability item a)

Condition: Where web pages or ICT with RTT functionality interoperate with other ICT with RTT functionality (as required by clause 6.2.1.1)

Where ICT with RTT functionality interoperates with other ICT with RTT functionality (as required by clause 6.2.1.1) they shall support the applicable RTT interoperability mechanisms described below:

a. ICT interoperating with other ICT directly connected to the Public Switched Telephone Network (PSTN), using Recommendation ITU-T V.18 or any of its annexes for text telephony signals at the PSTN interface

Note: In practice, new standards are introduced as an alternative codec/protocol that is supported alongside the existing common standard and used when all end-to-end components support it while technology development, combined with other reasons including societal development and cost efficiency, may make others become obsolete.

Note: Where multiple technologies are used to provide voice communication, multiple interoperability mechanisms may be needed to ensure that all users are able to use RTT.

Example: A conferencing system that supports voice communication through an internet connection might provide RTT over an internet connection using a proprietary RTT method (option c). However, regardless of whether the RTT method is proprietary or non-proprietary, if the conferencing system also offers telephony communication it will also need to support options a or b to ensure that RTT is supported over the telephony connection.

6.2.3 Interoperability item b)

Condition: Where web pages or ICT with RTT functionality interoperate with other ICT with RTT functionality (as required by clause 6.2.1.1)

Where ICT with RTT functionality interoperates with other ICT with RTT functionality (as required by clause 6.2.1.1) they shall support the applicable RTT interoperability mechanisms described below:

b. ICT interoperating with other ICT using VOIP with Session Initiation Protocol (SIP) and using RTT that conforms to IETF RFC 4103. For ICT interoperating with other ICT using the IP Multimedia Sub-System (IMS) to implement VOIP, the set of protocols specified in ETSI TS 126 114, ETSI TS 122 173 and ETSI TS 134 229 describe how IETF RFC 4103 would apply

Note: In practice, new standards are introduced as an alternative codec/protocol that is supported alongside the existing common standard and used when all end-to-end components support it while technology development, combined with other reasons including societal development and cost efficiency, may make others become obsolete.

Note: Where multiple technologies are used to provide voice communication, multiple interoperability mechanisms may be needed to ensure that all users are able to use RTT.

Example: A conferencing system that supports voice communication through an internet connection might provide RTT over an internet connection using a proprietary RTT method (option c). However, regardless of whether the RTT method is proprietary or non-proprietary, if the conferencing system also offers telephony communication it will also need to support options a or b to ensure that RTT is supported over the telephony connection.

6.2.3 Interoperability item c)

Condition: Where web pages or ICT with RTT functionality interoperate with other ICT with RTT functionality (as required by clause 6.2.1.1)

Where ICT with RTT functionality interoperates with other ICT with RTT functionality (as required by clause 6.2.1.1) they shall support the applicable RTT interoperability mechanisms described below:

c. ICT interoperating with other ICT using technologies other than a or b, above, using a relevant and applicable common specification for RTT exchange that is published and available for the environments in which they will be operating. This common specification shall include a method for indicating loss or corruption of characters

Note: In practice, new standards are introduced as an alternative codec/protocol that is supported alongside the existing common standard and used when all end-to-end components support it while technology development, combined with other reasons including societal development and cost efficiency, may make others become obsolete.

Note: Where multiple technologies are used to provide voice communication, multiple interoperability mechanisms may be needed to ensure that all users are able to use RTT.

Example: A conferencing system that supports voice communication through an internet connection might provide RTT over an internet connection using a proprietary RTT method (option c). However, regardless of whether the RTT method is proprietary or non-proprietary, if the conferencing system also offers telephony communication it will also need to support options a or b to ensure that RTT is supported over the telephony connection.

6.2.3 Interoperability item d)

Condition: Where web pages or ICT with RTT functionality interoperate with other ICT with RTT functionality (as required by clause 6.2.1.1)

Where ICT with RTT functionality interoperates with other ICT with RTT functionality (as required by clause 6.2.1.1) they shall support the applicable RTT interoperability mechanisms described below:

d. ICT interoperating with other ICT using a standard for RTT that has been introduced for use in any of the above environments, and is supported by all of the other active ICT that support voice and RTT in that environment.

Note: In practice, new standards are introduced as an alternative codec/protocol that is supported alongside the existing common standard and used when all end-to-end components support it while technology development, combined with other reasons including societal development and cost efficiency, may make others become obsolete.

Note: Where multiple technologies are used to provide voice communication, multiple interoperability mechanisms may be needed to ensure that all users are able to use RTT.

Example: A conferencing system that supports voice communication through an internet connection might provide RTT over an internet connection using a proprietary RTT method (option c). However, regardless of whether the RTT method is proprietary or non-proprietary, if the conferencing system also offers telephony communication it will also need to support options a or b to ensure that RTT is supported over the telephony connection.

6.2.4 RTT responsiveness

Condition: Where web pages or ICT utilise RTT input

Where ICT utilises RTT input, that RTT input shall be transmitted to the ICT network or platform on which the ICT runs within 500 ms of the time that the smallest reliably composed unit of text entry is available to the ICT for transmission. Delays due to platform or network performance shall not be included in the 500 ms limit.

Note: For character by character input, the "smallest reliably composed unit of text entry" would be a character. For word prediction it would be a word. For some voice recognition systems - the text may not exit the recognition software until an entire word (or phrase) has been spoken. In this case, the smallest reliably composed unit of text entry available to the ICT would be the word (or phrase).

Note: The 500 ms limit allows buffering of characters for this period before transmission so character by character transmission is not required unless the characters are generated more slowly than 1 per 500 ms.

Note: A delay of 300 ms, or less, produces a better impression of flow to the user.

6.3 Caller ID

Condition: Where web pages or ICT provide caller identification or similar telecommunications functions

Where ICT provides caller identification or similar telecommunications functions, the caller identification and similar telecommunications functions shall be available in text form as well as being programmatically determinable, unless the functionality is closed.

6.4 Alternatives to voice-based services

Condition: Where web pages or ICT provide real-time voice-based communication and also provide voice mail, auto-attendant, or interactive voice response facilities

Where ICT provides real-time voice-based communication and also provides voice mail, auto-attendant, or interactive voice response facilities, the ICT shall offer users a means to access the information and carry out the tasks provided by the ICT without the use of hearing or speech.

Note: Tasks that involve both operating the interface and perceiving the information would require that both the interface and information be accessible without use of speech or hearing.

Note: Solutions capable of handling audio, RTT and video media could satisfy the above requirement.

6.5.2 Resolution item a)

Condition: Where web pages or ICT that provide two-way voice communication includes real-time video functionality

Where ICT that provides two-way voice communication includes real-time video functionality, the ICT:

shall support at least QVGA resolution

6.5.3 Frame rate item a)

Condition: Where ICT that provides two-way voice communication includes real-time video functionality, the ICT:

shall support a frame rate of at least 20 Frames Per Second (FPS)

6.5.4 Synchronization between audio and video

Condition: Where ICT that provides two-way voice communication includes real-time video functionality, the ICT shall ensure a maximum time difference of 100 ms between the speech and video presented to the user.

Note: Recent research shows that, if audio leads the video, the intelligibility suffers much more than the reverse.

6.5.5 Visual indicator of audio with video

Condition: Where web pages or ICT that provide two-way voice communication includes real-time video functionality

Where ICT provides two-way voice communication, and includes real-time video functionality, the ICT shall provide a real-time visual indicator of audio activity.

Note: The visual indicator may be a simple visual dot or LED, or other type of on/off indicator, that flickers to reflect audio activity.

Note: Without this indication a person who lacks the ability to hear does not know when someone is talking.

6.5.6 Speaker identification with video (sign language) communication

Condition: Where web pages or ICT provide speaker identification for voice users

Where ICT provides speaker identification for voice users, it shall provide a means for speaker identification for realtime signing and sign language users once the start of signing has been indicated.

Note: The speaker ID can be in the same location as for voice users for multiparty calls.

Note: This mechanism might be triggered manually by a user, or automatically where this is technically achievable.

7.1.1 Captioning with playback

Condition: Where web content or ICT displays video with synchronized audio

Where ICT displays video with synchronized audio, it shall have a mode of operation to display the available captions. Where closed captions are provided as part of the content, the ICT shall allow the user to choose to display the captions.

Note: Captions may contain information about timing, colour and positioning. This caption data is necessary for caption users. Timing is used for caption synchronization. Colour can be used for speaker identification. Position can be used to avoid obscuring important information.

Note: If a Braille device is connected, the ICT should provide an option to display captions on the Braille device.

Note: Clause 7.1.1 refers to the ability of the player to display captions. Clauses 9.1.2.2, 10.1.2.2 and 11.1.2.2 refer to the provision of captions for the content (the video).

7.1.2 Captioning synchronization

Condition: Where web content or ICT displays captions

Where ICT displays captions, the mechanism to display captions shall preserve synchronization between the audio and the corresponding captions as follows:

Captions in recorded material: within 100 ms of the time stamp of the caption.
Live captions: within 100 ms of the availability of the caption to the player.

7.1.3 Preservation of captioning

Condition: Where web pages or ICT transmit, convert or record video with synchronized audio

Where ICT transmits, converts or records video with synchronized audio, it shall preserve caption data such that it can be displayed in a manner consistent with clauses 7.1.1 and 7.1.2. Additional presentational aspects of the text such as screen position, text colours, text style and text fonts may convey meaning, based on regional conventions. Altering these presentational aspects could change the meaning and should be avoided wherever possible.

7.1.4 Captions characteristics

Condition: Where web content or ICT displays captions

Where ICT displays captions, it shall provide a way for the user to adapt the displayed characteristics of captions to their individual requirements, except where the captions are displayed as unmodifiable characters.

Note: Defining the background and foreground colour of subtitles, font type, size opacity of the background box of subtitles, and the contour or border of the fonts can contribute to meeting this requirement.

Note: Subtitles that are bitmap images are examples of unmodifiable characters.

7.1.5 Spoken subtitles

Condition: Where web content or ICT displays video with synchronized audio

Where ICT displays video with synchronized audio, it shall have a mode of operation to provide a spoken output of the available captions, except where the content of the displayed captions is not programmatically determinable.

Note: Being able to manage speech output range for spoken subtitles independently from general ICT speech is preferable for most users. That is possible when the audio file with spoken subtitle is delivered in a separate audio track and mixed in the end users device.

Note: Presenting the separate audio track with spoken subtitles in synchronization with the displayed subtitles/captions improves understandability of the subtitles.

Note: Providing subtitles/captions as separate text-streams, facilitates converting the respective texts into audio.

Note: Subtitles that are bitmap images are examples where the content of the displayed captions will not be programmatically determinable.

7.2.1 Audio description playback

Condition: Where web content or ICT displays video with synchronized audio

Where ICT displays video with synchronized audio, it shall provide a mechanism to select and play available audio description to the default audio channel. Where video technologies do not have explicit and separate mechanisms for audio description, an ICT is deemed to satisfy this requirement if the ICT enables the user to select and play several audio tracks.

7.2.2 Audio description synchronization

Condition: Where web content or ICT has a mechanism to play audio description

Where ICT has a mechanism to play audio description, it shall preserve the synchronization between the audio/visual content and the corresponding audio description.

7.2.3 Preservation of audio description

Condition: Where web pages or ICT transmit, convert, or record video with synchronized audio

Where ICT transmits, converts, or records video with synchronized audio, it shall preserve audio description data such that it can be played in a manner consistent with clauses 7.2.1 and 7.2.2.

7.3 User controls for captions and audio description

Condition: Where web pages or ICT primarily display materials containing video with associated audio content

Where ICT primarily displays materials containing video with associated audio content, user controls to activate subtitling and audio description shall be provided to the user at the same level of interaction (i.e. the number of steps to complete the task) as the primary media controls.

Note: Primary media controls are the set of controls that the user most commonly uses to control media.

Note: Products that have a general hardware volume control, such as a telephone, or a laptop which can be configured to display video through software but which is not its primary purpose, would not need dedicated hardware controls for captions and descriptions; however software controls, or hardware controls mapped through software, would need to be at the same level of interaction.

Note: It is best practice for ICT to include additional controls enabling the user to select whether captions and audio description are turned on or off by default.

Clause 11 - Software

Note FFG: Some relevant criteria from Clause 11 correspond to WCAG 2.1 A + AA. These are listed above under the WCAG criteria and are no longer listed here.

Six WCAG criteria are excluded for mobile applications:

2.4.1 Bypass Blocks
2.4.2 Page Titled
2.4.5 Multiple Ways
3.1.2 Language of Parts
3.2.3 Consistent Navigation
3.2.4 Consistent Identification

11.1.1.1.2 Non-text content (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading, it shall meet requirement 5.1.3.6 (Speech output for non-text content).

11.1.2.1.2.1 Pre-recorded audio-only (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading and where pre-recorded auditory information is needed to enable the use of closed functions of ICT, the functionality of software that provides a user interface shall meet requirement 5.1.5 (Visual output for auditory information).

11.1.2.1.2.2 Pre-recorded video-only (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading and where pre-recorded auditory information is needed to enable the use of closed functions of ICT, the functionality of software that provides a user interface shall meet requirement 5.1.5 (Visual output for auditory information).

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading, it shall meet requirement 5.1.3.7 (Speech output for video information).

11.1.2.3.2 Audio description or media alternative (pre-recorded - closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading, it shall meet requirement 5.1.3.7 (Speech output for video information).

11.1.3.5.2 Identify input purpose (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface and is closed to assistive technologies, in at least one mode of operation the ICT shall present to the user, in an audio form, the purpose of each input field collecting information about the user when the input field serves a purpose identified in the WCAG 2.1 Input Purposes for User Interface Components section.

11.1.4.4.2 Resize text (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is not able to access the enlargement features of platform or assistive technology, it shall meet requirement 5.1.4 (Functionality closed to text enlargement).

Note: Because the text rendering support in a closed environment may be more limited than the support found in user agents for the Web, meeting the present clause in a closed environment may place a much heavier burden on the content author.

11.1.4.5.2 Images of text (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading, it shall meet requirement 5.1.3.6 (Speech output for non-text content).

11.2.1.1.2 Keyboard (closed funtionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to keyboards or keyboard interface, it shall meet requirement 5.1.6.1 (Operation without keyboard interface: Closed functionality).

11.2.1.4.2 Character key shortcuts (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to keyboards or keyboard interface, it shall meet requirement 5.1.6.1 (Operation without keyboard interface: Closed functionality).

11.3.1.1.2 Language of software (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading, it shall meet requirement 5.1.3.14 (Spoken languages).

11.3.3.1.2 Error Identification (closed functionality)

Condition: Only for mobile applications: Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading

Where ICT is non-web software that provides a user interface which is closed to assistive technologies for screen reading, it shall meet requirement 5.1.3.15 (Non-visual error identification).