The intent of this Success Criterion (SC) is to ensure that when people override author specified text spacing to improve their reading experience, content is still readable and operable. Each of the requirements stipulated in the SC's four bullets helps ensure text styling can be adapted by the user to suit their needs.
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The specified metrics set a minimum baseline. The values in between the author's metrics and the metrics specified in this SC should not have loss of content or functionality.
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The intent of this Success Criterion (SC) is to ensure that when people override author-specified text spacing to improve their reading experience, content is still readable and operable. Each of the requirements stipulated in the SC's four bullets helps ensure text styling can be adapted by the user to suit their needs.
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The metrics set a target for a minimum increase in text spacing that must be met. Starting from the author's baseline implementation, any increase in spacing for any of these four style properties up to and including these targets should not result in the loss of content or functionality.
This SC focuses on the adaptability of content to an increase in spacing between lines, words, letters, and paragraphs. Any combination of these may assist a user with effectively reading text. As well, ensuring that content correctly adapts when users override author settings for spacing also significantly increases the likelihood other style preferences can be set by the user. For example, a user may need to change to a wider font family than the author has set in order to effectively read text.
Author Responsibility
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This SC does not dictate that authors must set all their content to the specified metrics, nor does the SC intend to imply that all users will adjust the specified metrics. Rather, it specifies that should a user choose to set any of these metrics they can do so without any loss of content or functionality. The author requirement is both to not interfere with a user's ability to override the author settings, and to ensure that content thus modified does not break content in the manners shown in figures 1 through 3 in Effects of Not Allowing for Spacing Override.
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In some human languages and scripts, some of the metrics specified by the SC are inapplicable. For example, languages such as Japanese do not use spacing following paragraphs, meaning that users are unlikely to make any paragraph spacing changes in practice. The exception in this SC allows authors to ignore text style properties which are inapplicable to the combination of language and script being used.
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It is beneficial for users if authors use any locally available guidance for improving readability in the local language or writing system. If the user chooses to go beyond the metrics specified, any resulting loss of content or functionality is the user's responsibility.
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Further, this SC is not concerned with how users change the line height and spacing metrics. It does not require that content implement its own mechanisms to allow users to do this. It is not a failure of the content if a user agent or platform does not provide a way for users to do this. Content does not fail this SC if the method chosen by the user - for instance, the use of an extension or bookmarklet - fails to correctly set the line height and spacing text properties on the content (provided that the content is not actively and purposely preventing the properties from being added).
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This SC does not dictate that authors must set all their content to the specified metrics, or provide a mechanism to do so. Rather, it specifies that an author's content has the ability to be set to those metrics without loss of content or functionality. The author requirement is both to not interfere with a user's ability to override the author settings, and to ensure that content thus modified does not break content in the manners shown in figures 1 through 3 in Effects of Not Allowing for Spacing Override. The values in the SC are a baseline. Authors are encouraged to allow spacing to surpass the values specified, not see them as a ceiling.
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It is beneficial for users if authors use any locally available guidance for improving readability in the local language or writing system. Conversely, in some human languages and scripts, some of the metrics specified by the SC are inapplicable. For example, languages such as Japanese do not use spacing following paragraphs, meaning that users are unlikely to make any paragraph spacing changes in practice. The exception in this SC allows authors to ignore text style properties which are inapplicable to the combination of language and script being used.
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Applicability
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If the markup-based technologies being used are capable of overriding text to the Success Criterion's metrics, then this SC is applicable. For instance Cascading Style Sheet/HTML technologies are quite able to allow for the specified spacing metrics. Plugin technologies would need to have a built-in ability to modify styles to the specified metrics. Currently, this SC does not apply to PDF as it is not implemented using markup.
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Examples of text that are typically not affected by style properties and not expected to adapt are:
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User Responsibility
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The user may choose to exceed the spacing adjustments in the SC. The ability to read and derive meaning from the overridden spacing rests with the user. If large increases in spacing reduce readability, or cause loss of content or functionality, the user can adjust or return to spacing within the bounds of the SC. How such changes are achieved is up to the user, who may choose a user stylesheet, bookmarklet, extension, or application. Regardless, the user needs the flexibility to adjust spacing -- and within the bounds set in the SC, without loss of content or functionality.
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Further, this SC does not require that content implement its own mechanisms to allow users to do this. It is not a failure of the content if a user agent or platform does not provide a way for users to do this. Content does not fail this SC if the method chosen by the user - for instance, the use of an extension or bookmarklet - fails to correctly set the line height and spacing text properties on the content (provided that the content is not actively and purposely preventing the properties from being added).
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Applicability
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If the markup-based technologies being used are capable of overriding text to the Success Criterion's metrics, then this SC is applicable. For instance Cascading Style Sheet/HTML technologies are quite able to allow for the specified spacing metrics. Plugin technologies would need to have a built-in ability to modify styles to the specified metrics. Currently, this SC does not apply to PDF, as the portable document format is not implemented using markup.
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Examples of text typically not affected by style properties and not expected to adapt are:
Video captions embedded directly into the video frames and not provided as an associated caption file
Where text is not truncated but it is when text is spaced, if there is no mechanism to show the truncated text, it fails this Success Criterion.
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User Responsibility
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The ability to read and derive meaning from the overridden spacing rests with the user. The user may choose to exceed the spacing adjustments in the SC. If the increased spacing causes loss of content or functionality, the user will adjust or return to the author’s original spacing or spacing within the bounds of the SC. Regardless, the user needs the flexibility to adjust spacing within the bounds set in the SC without loss of content or functionality. Such changes may be achieved via user stylesheet, bookmarklet, extension, or application.
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Effects of Not Allowing for Spacing Override
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The following images show some types of failures when authors do not take into consideration that users may override spacing to the metrics specified in this Success Criterion.
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The following images show some types of failures when authors do not take into consideration that users may override spacing to the metrics specified in this Success Criterion.
Text Cut Off
The bottom portion of the words "Your Needs" is cut off in a heading making that text unreadable in Figure 1. It should read "We Provide a Mobile Application Service to Meet Your Needs."
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Text Cut Off
Vertical text cut off is a failure.
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In Figure 2 the last portion of text is cut off in three side-by-side headings. The first heading should read "A cog in the wheel", but it reads "A cog in the whe". Only half of the second "e" is visible and the letter "l" is completely missing. The second heading should read "A penny for your thoughts". But it reads "A penny for your". The third should read "Back to the drawing board." But it reads "Back to the drawi".
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In Figure 2 the last portion of text is cut off in three side-by-side headings. The first heading should read "A cog in the wheel" but it reads "A cog in the whe". Only half of the second "e" is visible and the letter "l" is completely missing. The second heading should read "A penny for your thoughts" but it reads "A penny for your". The third should read "Back to the drawing board." but it reads "Back to the drawi".
Horizontal text cut off is a failure.
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Benefits
People with low vision who require increased space between lines, words, and letters are able to read text.
People with dyslexia may increase space between lines, words, and letters to increase reading speed.
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Although not required by this SC, white space between blocks of text can help people with cognitive disabilities discern sections and call out boxes.
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Although not required by this SC, white space between blocks of text can help people with cognitive disabilities discern sections and call-out boxes.
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