Fwd: lvtf-ACTION-115: Update 1.4.12 understanding with wayne

---------- Forwarded message ---------
From: Jim Allan <jimallan@tsbvi.edu>
Date: Thu, Aug 1, 2019 at 10:42 AM
Subject: Re: lvtf-ACTION-115: Update 1.4.12 understanding with wayne
To: Wayne Dick <wayneedick@gmail.com>


my first pass at the intent update. also attached a word version with
reveal codes.

Jim

original understanding
Intent

The intent of this Success Criterion (SC) is to ensure that people can
override text spacing to improve their reading experience. 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.

This SC focuses on the ability to increase spacing between lines, words,
letters, and paragraphs. Any combination of these may assist a user with
effectively reading text. As well, ensuring users can override author
settings for spacing also signficantly 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

This SC does not dictate that authors must set all their content to the
specified metrics. 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 4 in Effects of Not Allowing for Spacing Override.
Applicability

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.

Examples of text that are typically not affected by style properties
<https://www.w3.org/WAI/WCAG21/Understanding/text-spacing.html#dfn-style-property>
and
not expected to adapt are:

   - Video captions embedded directly into the video frames and not
   provided as an associated caption file
   - Images of text
   <https://www.w3.org/WAI/WCAG21/Understanding/text-spacing.html#dfn-image-of-text>

For this SC, canvas
<https://www.w3.org/TR/html5/scripting-1.html#the-canvas-element>
implementations
of text are considered to be images of text
<https://www.w3.org/WAI/WCAG21/Understanding/text-spacing.html#dfn-image-of-text>
.
User Responsibility

The ability to read and derive meaning from the overridden spacing rests
with the user. If the increased spacing impacts those abilities, the user
will adjust or they will return to the default view. Regardless, the user
needs the flexibility to adjust spacing within the bounds set in the SC.
Such changes may be acheived via user stylesheet, bookmarklet, extension,
or application.

-------------

Updated Understanding

*Intent*

The intent of this Success Criterion (SC) is to ensure that people can
override *author specified* text spacing to improve their reading
experience. 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.

*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.*


This SC focuses on the ability to increase spacing between lines, words,
letters, and paragraphs. Any combination of these may assist a user with
effectively reading text. As well, ensuring users can 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

This SC *does not* dictate that authors must set all their content to the
specified metrics. 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 4 in Effects of Not Allowing for Spacing Override. *The values in
the SC are a baseline. We want to encourage authors to surpass these, not
see them as a ceiling to build to. If the user chooses to go beyond the
SC’s metrics any resulting loss of content or functionality is the users
responsibility.*



*Applicability*

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.

Examples of text that are typically not affected by style properties
<https://www.w3.org/WAI/WCAG21/Understanding/text-spacing.html#dfn-style-property>
and
not expected to adapt are:

·         Video captions embedded directly into the video frames and not
provided as an associated caption file

·         Images of text
<https://www.w3.org/WAI/WCAG21/Understanding/text-spacing.html#dfn-image-of-text>

For this SC, canvas
<https://www.w3.org/TR/html5/scripting-1.html#the-canvas-element>
implementations
of text are considered to be images of text
<https://www.w3.org/WAI/WCAG21/Understanding/text-spacing.html#dfn-image-of-text>
.


User Responsibility

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.

On Thu, Jul 25, 2019 at 11:04 AM Low Vision Accessibility Task Force Issue
Tracker <sysbot+tracker@w3.org> wrote:

> lvtf-ACTION-115: Update 1.4.12 understanding with wayne
>
> https://www.w3.org/WAI/GL/low-vision-a11y-tf/track/actions/115
>
> Assigned to: Jim Allan
>
-- 
Jim Allan, Accessibility Coordinator
Texas School for the Blind and Visually Impaired
1100 W. 45th St., Austin, Texas 78756
voice 512.206.9315    fax: 512.206.9452 http://www.tsbvi.edu/
"We shape our tools and thereafter our tools shape us." McLuhan, 1964