Red strobe light.

Section 508: Flashing provision

One provision in the Section 508/255 refresh is to prevent flashing in patterns that may cause some people with photosensitive epilepsy to have a seizure. It is in the chapter that applies to hardware. The proposed provision states:

405.1 General. Where ICT emits lights in flashes, there shall be no more than three flashes in any one-second period.
EXCEPTION: Flashes that do not exceed the general flash and red flash thresholds defined in WCAG 2.0 (incorporated by reference in Chapter 1) are not required to conform to 405.

The main problem with this provision is that it is too strict. The WCAG 2.0 provisions do not have any guidance for hardware with flashing lights that do not occur on a screen (e.g., indicator LEDs). Strictly interpreted, the provision would apply to all indicator lights, including those that flicker to indicate network, data, or sound activity. Such indicator lights  would not be allowed to flash more than three times in a one-second timeframe.

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It important to keep this provision; otherwise, there would be no limitations to the frequency or flashing pattern of lights that might be used to alert or warn users. This could lead to triggering a seizures. However, it would be good to add an exception for some types of indication lights.

Categories of Hardware Lights

Lights on hardware may fall into different categories, including:

  1. Illumination
  2. Warning & Alerting
  3. Indicators of status
  4. Indicators of real-time activity

The flashing pattern and frequency of lights in the first three categories can be arbitrarily chosen, so they can easily meet 405.1 as it is currently worded. Even very bright lights that might be used to get somebody’s attention in warning or alerting circumstances can be flashed in patterns that meet the provision.

The problem is with the fourth category: lights that indicate real-time activity, such as lights that indicate network activity, hard drive IO, and LED VU meters and clipping lights on some sound equipment. The pattern or frequency of flashing may occur more than three times in a one-second timeframe, but the pattern cannot be changed without changing the entire nature of the lights and their purpose.

In typical products, the lights that indicate real-time activity are neither large nor very bright. Having large (in visual area) real-time activity lights would be the worst case since the trigger brightness thresholds for areas is relatively low, so these “large” indicators should not be exempted from the provision. Because of the danger to people with photosensitive epilepsy, and the difficulty calculating seizure thresholds in these circumstances, manufacturers should avoid having large flashing indicators of real-time activity.

Point light sources can be made to be potentially very bright in such a way that they may cause disability glare in the eyes of viewers that may make flash seem much larger than the actual point source. However, from a practical standpoint, such indicators of real-time activity are not typically that bright because they are annoying and potentially painful to all users. Because of the practical consideration, it seems reasonable that a narrow exception can be made to provision 405.1 for point-source lights that indicate real-time activity.

Recommendation

The recommended provision adds Exception 2.

405.1 General. Where ICT emits lights in flashes, there shall be no more than three flashes in any one-second period.
EXCEPTION 1: Flashes that do not exceed the general flash and red flash thresholds defined in WCAG 2.0 (incorporated by reference in Chapter 1) are not required to conform to 405.
EXCEPTION 2: Flickering of point light sources (where a point light source subtends no more than 1-degree of visual angle at the typical viewing distance) that indicate real-time activity (such as sound, hard drive, or network activity) are not required to conform to 405.

Ishihara plate for testing color-blindness.

Section 508: Color blindness

As rumor would have it, the Access Board released the Section 508 refresh Notice of Proposed Rulemaking (NPRM) today. I have only just taken a quick look at it so far and will have other comments in the future. I did want to make one observation that pertains to two proposed provisions:

302.3 Without Perception of Color. Where a visual mode of operation is provided, ICT shall provide at least one mode of operation that does not require user perception of color. (From the Functional Performance Criteria chapter of Appendix A.)

407.7 Color. Color coding shall not be used as the only means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (From the Hardware chapter of Appendix A.)

These are important provisions and good for a sizable population (estimates range from about 5-10% of males have some form of color blindness). However, as currently worded, the provisions would allow for a non-visual means of perceiving or distinguishing a colored element. At an extreme, this could make a color-blind user have to use a text-to-speech mode that users who are blind might use. Should a person with color blindness have to put on headphones and use a screen reader in order to access an interface?

The fix is simple in for both cases—add the word visual to the provisions.

  • 302.3 Without Perception of Color. Where a visual mode of operation is provided, ICT shall provide at least one visual mode of operation that does not require user perception of color. (From the Functional Performance Criteria chapter of Appendix A.)
  • 407.7 Color. Color coding shall not be used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (From the Hardware chapter of Appendix A.)
Section 508.

What is Section 508?

Section 508 is legislation for accessible electronic and information technologies. It applies to all U.S. Federal agencies when they develop, procure, purchase, and maintain such technology. The legislation is an example of pull legislation—the  federal government is a big purchaser of technology, so companies who want to sell to the government must make an effort to include accessibility in their product. This should hopefully increase the accessibility of products available to others as well. While the legislation specifically applies to federal agencies, state and local governments and other organizations may also require Section 508 compliance when they are procuring technology.

The current Section 508 standards are showing their age. The U.S. Access Board (an independent agency of the government devoted to accessibility for people with disabilities) has been undertaking a multi-year refresh of Section 508 with reports and drafts that have been published in 2008, 2010, and 2011. Recent rumors have been pointing to a notice of proposed rulemaking being published on February 18, 2015.

When published, there will probably be a 90-day public comment period.

As part of my work at the Trace Center, I have been working on the Section 508 standards during the refresh process: analyzing the provisions and suggesting changes and rationale. I was the main author of the Trace Center’s comments on the 2011 proposal. I plan to analyze the next version when it comes out (hopefully soon). I will post some of my thoughts and analysis of the proposed standards here on my blog.