Ensure that the user can select preferred styles (e.g., colors, size of rendered text, and synthesized speech characteristics) from choices offered by the user agent. Allow the user to override author-specified styles and user agent default styles.
Providing access to content (see guideline 2) includes enabling users to configure and control its rendering. Users with low vision may require that text be rendered at a size larger than the size specified by the author or by the user agent's default rendering. Users with color blindness may need to impose or prevent certain color combinations.
For dynamic presentations such as synchronized multimedia presentations created with SMIL 1.0 [SMIL], users with cognitive, hearing, visual, and physical disabilities may not be able to interact with a presentation within the time frame assumed by the author. To make the presentation accessible to these users, user agents rendering multimedia content (audio, video, and other animations), have to allow the user to control the playback rate of this content, and also to stop, start, pause, and navigate it quickly. User agents rendering audio have to allow the user to control the audio volume globally and to allow the user to control distinguishable audio tracks.
User agents with speech synthesis capabilities need to allow users to control various synthesized speech rendering parameters. For instance, some users may not be able to make use of high or low frequencies; these users have to be able to configure their speech synthesizers to use suitable frequencies.
4.1
[P1] | - Allow global configuration of the scale of visually rendered text content. Preserve distinctions in the size of rendered text as the user increases or decreases the scale.
- As part of satisfying provision one of this checkpoint, provide a configuration option to override rendered text sizes specified by the author or user agent defaults.
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As part of satisfying provision one of this checkpoint, offer a range of text sizes to the user that includes at least:
- the range offered by the conventional utility available in the operating environment that allows users to choose the text size (e.g., the font size), or
- if no such utility is available, the range of text sizes supported by the conventional APIs of the operating environment for drawing text.
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4.2
[P1] | - Allow global configuration of the font family of all visually rendered text content.
- As part of satisfying provision one of this checkpoint, provide a configuration option to override font families specified by the author or by user agent defaults.
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As part of satisfying provision one of this checkpoint, offer a range of font families to the user that includes at least:
- the range offered by the conventional utility available in the operating environment that allows users to choose the font family, or
- if no such utility is available, the range of font families supported by the conventional APIs of the operating environment for drawing text.
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4.3
[P1] | - Allow global configuration of the foreground and background color of all visually rendered text content.
- As part of satisfying provision one of this checkpoint, provide a configuration option to override foreground and background colors specified by the author or user agent defaults.
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As part of satisfying provision one of this checkpoint, offer a range of colors to the user that includes at least:
- the range offered by the conventional utility available in the operating environment that allows users to choose colors, or
- if no such utility is available, the range of colors supported by the conventional APIs of the operating environment for specifying colors.
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4.4
[P1] | - Allow the user to slow the presentation rate of rendered audio and animation content (including video and animated images).
- As part of satisfying provision one of this checkpoint, for a visual track, provide at least one setting between 40% and 60% of the original speed.
- As part of satisfying provision one of this checkpoint, for a prerecorded audio track including audio-only presentations, provide at least one setting between 75% and 80% of the original speed.
- When the user agent allows the user to slow the visual track of a synchronized multimedia presentation to between 100% and 80% of its original speed, synchronize the visual and audio tracks (per checkpoint 2.6). Below 80%, the user agent is not required to render the audio track.
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4.5
[P1] | - Allow the user to stop, pause, and resume rendered audio and animation content (including video and animated images) that last three or more seconds at their default playback rate.
- Allow the user to navigate efficiently within rendered audio and animations (including video and animated images) that last three or more seconds at their default playback rate.
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4.6
[P1] | - For graphical viewports, allow configuration so that captions synchronized with a visual track in content are not obscured by it.
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4.7
[P1] | - Allow global configuration of the volume of all rendered audio, with an option to override audio volumes specified by the author or user agent defaults.
- As part of satisfying provision one of this checkpoint, allow the user to choose zero volume (i.e., silent).
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4.8
[P1] | - Allow independent control of the volumes of rendered audio content synchronized to play simultaneously.
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4.9
[P1] | - Allow configuration of the synthesized speech rate, according to the full range offered by the speech synthesizer.
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4.10
[P1] | - Allow control of the synthesized speech volume, independent of other sources of audio.
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4.11
[P1] | - Allow configuration of synthesized speech characteristics according to the full range of values offered by the speech synthesizer.
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4.12
[P2] | - Allow configuration of synthesized speech pitch. Pitch refers to the average frequency of the speaking voice.
- Allow configuration of synthesized speech pitch range. Pitch range specifies a variation in average frequency.
- Allow configuration of synthesized speech stress. Stress refers to the height of "local peaks" in the intonation contour of the voice.
- Allow configuration of synthesized speech richness. Richness refers to the richness or brightness of the voice.
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4.13
[P2] | - Provide support for user-defined extensions to the synthesized speech dictionary.
- Provide support for spell-out: where text is spelled one character at a time, or according to language-dependent pronunciation rules.
- Allow at least two configurations for speaking numerals: one where numerals are spoken as individual digits, and one where full numbers are spoken.
- Allow at least two configurations for speaking punctuation: one where punctuation is spoken literally, and one where punctuation is rendered as natural pauses.
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4.14
[P1] | - Allow the user to choose from and apply alternative author style sheets (such as linked style sheets).
- Allow the user to choose from and apply at least one user style sheet.
- Allow the user to turn off (i.e., ignore) author and user style sheets.
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