Some comments and instructions in this page are for audio browsers and users who browse this site with screen readers. If you can see this paragraph and you are not using a text-only or screen reader browser, either the style sheet for screen viewing didn't load (if so, click on "refresh" to reload the style sheet), or you need to use a World Wide Web Consortium (W3C) standards-supporting browser that has full XHTML 1.0 Transitional and Strict and cascading style sheet (CSS) level 2 support.

For additional information, see the Accessibility Design and Features page.

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Accessibility Design and Features

Note:  All links going to other websites will open in the same window. Use the Back button to return to this website.

This site is designed with accessible features and considerations to give all visitors a similar browsing experience.

If you use assistive technology (such as a Braille reader, a screen reader, TTY, and so forth) and the format of any material on our website interferes with your ability to access the information, please contact the . To enable a response in a manner most helpful to you, please indicate the nature of your accessibility problem, the preferred format in which to receive the material, the Web address of the requested material, and your contact information.

Website Conventions

Links are checked periodically. Changes to the pages are marked with the following flags: New, Revised, and Updated.

Navigation features include a "skip" link at the top to go directly to the bottom of the page for the navigation links. Tab indexing levels have been added to all hyperlinks to aid users with screen readers to move logically through the pages. For people using audio assistive technology, there are skip links to go directly to the main content and to the navigation areas on the site. Cascading style sheets (CSS) replace table-defined page layout and spacer graphics so that pages will load as fast as possible and information will be in a logical order.

All links going to other websites will open in the current browser window. Use the Back button to return to this site. (See Target Window Attribute Removed below.)

Some people with disabilities prefer to use the keyboard to tab between links, form fields, and other page elements because they have problems using a mouse. All links have a tabindex.

Cascading Style Sheet (CSS) is used to style the links. It provides definitions for the following states:

  • Underlined, a basic link that hasn't been clicked on or visited. These links have no background and a bright font color.
  • Active, a link that is currently being viewed in the navigation menu or that will be viewed when clicked on. These links have a distinctive background and font color.
  • Visited, a link that has been visited, but is no longer open. It may have been visited during the current browsing session or it may be listed in the history of previous sessions. These links have a dimmed background and font color.
  • Hover or Focus, is the link state when the mouse moves over the link borders. As you move or tab from link to link, the current link is said to have focus. Hover and focus states help make links more prominent so users can tell which link is the current one. The hover state gives the links a distinctive bright background and font color seen by sighted users. The focus state is for users who use the keyboard to move between links. Focus uses the same background and font colors as the hover state to give all users a similar browsing experience.

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Accessibility Features

This site aims to make the information it provides accessible to everyone including those with physical or mental disabilities and those with slow Internet connections. There are many challenges for Web developers and designers to handle when creating an accessible website such as the large variety of screen readers, browsers, platforms, and accessibility needs. What is accessible for one person may not be accessible for another. The site is designed using current standards on Internet Accessibility / Usability to be used by the average user and by users who work with screen readers or audio assistive technology.

Cascading Style Sheets

The entire website has been converted from a table-heavy design to a W3C-validated CSS (Cascading Style Sheets) design and layout. Cascading style sheets (CSS) replace table-defined page layout and spacer graphics so that pages will load as fast as possible and information will be in a logical order. Tables are used for presenting data only. CSS separates site content from presentation and offers the following benefits:

  • Consistent look and feel across the entire site
  • Smaller page size/lower bandwidth usage (less demand on servers)
  • Better user experience (smaller page size leads to faster site loading)
  • Better search engine optimization (increased information/markup ratio)
  • Cross-browser compatibility (CSS is supported by most browsers)
  • Future compatibility (valid, standard-compliant markup ensures reusable data)
  • Better accessibility and usability (screen-readers, access keys, alternative formats)
  • Better extensibility (i.e., printer-friendly, handheld-friendly)


The website does not use "Session" cookies to track your visit. Information is not saved for future visits.


The colors used in the website for links and change status flags are chosen using the:

For more information about color,  Revised see the Accessible Techcomm website's Web Accessibility: Color and Typography resources post.

Target Window Attribute Removed

In XHTML, the target="_blank" attribute for opening a link in a new window is not supported by XHTML. Opening a link in a new window to show it is not part of the current website is not liked by many users and it is not accessible for people with cognitive disabilities. Some people with cognitive disabilities have a difficult time remembering how they got to content off the current website. Because they are in a new window, the Back button will not return them to the place they were before going off the website they were on. For this reason, we are not opening offsite links in a new window. All links going to other websites will open in the same window. Use the Back button to return to our site. For more information about cognitive disabilities, see

Images and Multimedia

Images on the site provide alternative descriptive text. However, some browsers or screen readers cannot be relied upon to recognize alternative text. Many but not yet all images contain a title in the image links to compensate for these inconsistencies. A few images also have a long description to provide additional information about important images.

Multimedia aspects for the site are limited. There is no use of video or animation. There are a few sound files used to provide a bit of entertainment in a few places but they are not critical to the use of the site.


Frames are not used to separate sections of the window area to include several different web pages. Websites with frames are difficult to navigate with a screen reader unless you actually know that frames exist and which frames contain the information for which you are looking.

PDF Files

Most of the pages on this site are available in HTML or ASCII text format, which are easily read by people who use screen readers. However, some of our information is provided only in Adobe PDF format. Some of the newer PDF files are created with accessible features. Users can convert older PDF files to an accessible format using the Adobe® Acrobat® Reader™ with Accessibility.

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Specified Fonts and Page Width

Relative font sizes are used, which allows users to increase or decrease the font size in the browser's View menu. We have also made two style sheets for text only views: one for printing the page and one in a large font size for users who need larger text. For examples of readable and unreadable onscreen fonts, see the Compare fonts for use on your website post. Fonts used in this site are specified in ems, rems, and percents so they may be resized according to the user's preferences. In this site, we use Open Source Google fonts designed to make the Web look prettier and to speed up loading pages. Except in the Windows platform, the hierarchy for the fonts specified in the font family is "Roboto", "Helvetica Neue", "Lucida Sans", Helvetica, Geneva, Arial, sans-serif. In the Windows platform, the hierarchy for the fonts specified in the font family is "Roboto", Arial, Helvetica, Geneva, sans-serif. Your browser will use the first font in the list that you have installed on your computer. The fonts were designed to improve the challenges of onscreen display with clear distinctions between similar letters such as the lowercase i j l, the uppercase I J L, and the number 1 and is designed for easy screen readability. Roboto has a dual nature. It has a mechanical skeleton and the forms are largely geometric. At the same time, the font features friendly and open curves. While some grotesks distort their letterforms to force a rigid rhythm, Roboto doesn't compromise, allowing letters to be settled into their natural width. This makes for a more natural reading rhythm more commonly found in humanist and serif types. Using the code generated by Google Fonts, Google's servers will automatically send the smallest possible file to every user based on the technologies that their browser supports. For example, Google uses WOFF 2.0 compression when available. This makes the web faster for all users—particularly in areas where bandwidth and connectivity are an issue.

Page width is adjustable by the user. CSS layout allows text to reflow to fit the new space. When the window is made wider, the page will also become shorter as more text is put on a line. If you make the page too narrow, some elements may overlap. We have tried to make adjustments in the code to fix differences in the way various browsers handle spaces. If your browser shows the bottom navigation area or other areas of the page overlapping in places, reload the page and the CSS will adjust the flow.

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Accessibility and Browser Requirements

These pages are designed using Cascading Style Sheets level 2.1 and 3 without the use of tables for the page layout.

Browser Tests

This site aims to comply with current standards on Web accessibility. To ensure that we meet or exceed the guidelines of the World Wide Web Consortium Web Accessibility Initiative (W3C-WAI), we continually review our site and modify pages to remove accessibility problems for people with disabilities. Each page is tested for compliance with Section 508 and W3C 1-, 2-, and 3-level usability and accessibility requirements.

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