Last updated August 9, 2026.
We want this site to be usable by as many people as possible. We aim to meet the Web Content Accessibility Guidelines (WCAG) 2.1 Level AA. Accessibility is an ongoing effort and we keep working to improve it.
This site is built with standard semantic HTML, descriptive link text, and labeled regions so that assistive technology can navigate the page. It does not rely on a proprietary reader or plugin. Content responds to your browser's own zoom, font size, and contrast settings, and to the accessibility features built into your operating system.
Interactive elements such as the navigation links, the table of contents, and the back-to-top control can be reached with the Tab key and activated with Enter.
We test with current browsers. Some pages reference third-party content, including embedded video and linked research, that we do not control and that may not meet every guideline. We do not claim full or certified compliance with any standard or law.
If you find a barrier or need information in another format, contact [email protected]. Please name the page and describe the problem. We will respond and work to fix it.