Questions About Cancer? 1-800-4-CANCER

Accessibility (Section 508)

Basics of Section 508 Compliance

All NCI websites must be accessible to users, as described in Section 508 of the Rehabilitation Act, and compatible with screen readers and other assistive technologies. Section 508 requires federal agencies to make their electronic and information technologies, including websites, conform to certain accessibility standards. The following are the standards that NCI Web developers must follow to comply with Section 508 requirements. These standards are based on the Access Board's Web Accessibility Standards, which should also be read by NCI Web developers.

For more information about Section 508 and Web accessibility, see http://www.section508.gov/.

Linking to the Accessibility Policy

  • You must include a link named "Accessibility" from any Web page that may contain known accessibility barriers or that links to information inside your site that may present accessibility problems for users with disabilities (that is, any information that may not be 100 percent compliant with Section 508 standards).
  • The link must go to the NCI Web Accessibility Policy (http://cancer.gov/global/web/policies/accessibility) or to similar, locally written accessibility information. If you create your own accessibility information page, it must include a way for users with disabilities to contact you (e.g., response form, e-mail, telephone number).
  • Note: The "Accessibility" link is not an alternative to making your site accessible. It is to be used in addition to your best efforts to make it accessible.

General 508 Standards

The following numbered standards are direct quotes excerpted from Section 508 of the Rehabilitation Act, §1194.22. The bulleted points below them are added here as helpful guidelines for compliance with Section 508.

  1. §1194.22 (a) Offer Text Equivalents

    A text equivalent for every non-text element shall be provided (e.g., via "alt", "longdesc", or in element content).

    • Every image on a web site must have alternative text.
    • Decorative graphics with no other function should have empty alt descriptions (alt= ""), but they should never have missing alt descriptions.
    • Complex graphics (graphs, charts, etc.) should be accompanied by equivalent text descriptions.
    • The alt descriptions should succinctly describe the purpose of the objects, without being too verbose (for simple objects) or too vague (for complex objects).
    • Audio content must have captions and/or transcripts.
    • The longdesc attribute and/or in-line text should be used to describe images like charts or graphs where the alt-text does not carry equivalent information.

    "Alt Tag" Examples:

    Brain Tumor "Alt Tag" Example
    A pie chart shows percentages for different tumor types. About 60 percent of the pie chart denotes the percent of adult non-malignant brain tumors, 25 percent denotes adult malignant brain tumors, and about 10 percent  denotes childhood malignant brain tumors. About 5 percent of the pie denotes childhood non-malignant brain tumors.

    Blood Count "Alt Tag" Complete blood count (CBC). Blood is collected by inserting a needle into a vein and allowing the blood to flow into a tube. The blood sample is sent to the laboratory and the red blood cells, white blood cells, and platelets are counted. The CBC is used to test for, diagnose, and monitor many different conditions.

  2. §1194.22 (b) Present Synchronized Multimedia

    Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.

    • Text equivalents for multimedia content must be synchronized with the presentation, i.e., captions must be included.
    • Web authors are encouraged to include transcripts of audio content as well as synchronized alternatives because those transcripts allow searching and extracting.
  3. §1194.22 (c) Remain Independent of Color

    Web pages shall be designed so that all information conveyed with color is also available without color, for example from context or markup.

    • Important information should not be conveyed with color alone.
    • If color is used to convey important information, an alternative method conveying the same information should be provided.
    • Sufficient contrast should be provided.
  4. §1194.22 (d) Stay Independent of Style Sheets

    Documents shall be organized so they are readable without requiring an associated style sheet.
    Style sheets may be used for color, layout, and other presentation effects, but the document should still understandable (even if less visually appealing) when the style sheet is turned off.

    • Style sheets may be used for color, layout, and other presentation effects, but the document should still understandable (even if less visually appealing) when the style sheet is turned off.
    • Don't substitute style changes for the structural elements of HTML like headings, paragraphs, and lists.
    • If CSS is used for positioning, pages with style sheets disabled should be tested to be sure that information is not lost.
  5. §1194.22 (e) Provide Redundant Links for Server-Side Maps

    Redundant text links shall be provided for each active region of a server-side image map.

    • If a server-side map is used, equivalent text links for every active region on the map should be present.
    • Appropriate alternative text should be provided for the image.
  6. §1194.22 (f) Use Client-Side Image Maps

    Client-side image maps shall be provided instead of server-side image maps except where the regions cannot be defined with an available geometric shape.

    • Because polygons can be used to describe any area to as much detail as desired, it makes sense to use only client-side image maps instead of server-side maps.
    • Alternative text for each area of the map and the main map image itself should be provided.
  7. §1194.22 (g) Label Row and Column Headers

    Row and column headers shall be identified for data tables.

    • Data tables must have column and row headers appropriately identified using the proper table header markup.
    • Tables used strictly for layout purposes should NOT have rows or columns headers.
  8. §1194.22 (h) Use the Headers Attribute in Complex Tables

    Markup shall be used to associate data cells and header cells for data tables that have two or more logical levels of row or column headers.

    • Table cells should be associated with the appropriate headers (e.g., with the id, headers, scope, and/or axis HTML attributes).
    • If complex tables are used, the id attribute should be used on every header cell and the headers attribute on every data cell.
  9. §1194.22 (i) Supply Frame Titles (attributes and elements)

    Frames shall be titled with text that facilitates frame identification and navigation.

    • In order to facilitate navigation of a frame site, each frame element in the frameset needs a meaningful title attribute.
  10. §1194.22 (j) Reduce Flicker

    Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.

    • Animated gifs, Flash, or other features that cause a portion of the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz should be avoided. This condition can cause seizures in people with photosensitive epilepsy.
  11. §1194.22 (k) Offer a Text-only Alternative

    A text-only page, with equivalent information or functionality, shall be provided to make a web site comply with the provisions of this part, when compliance cannot be accomplished in any other way.

    • A text-only version should be created only when there is no other way to make the content accessible or when it offers significant advantages over the "main" version for certain disability types.
    • The text-only version should provide the functionality equivalent to that of the "main" version.
    • The “text-only” site must have all the information of the main site, must be updated with the same frequency as the main site, and must be immediately and obviously accessible from the main page.
  12. §1194.22 (l) Write Accessible Scripts

    When pages utilize scripting languages to display content or to create interface elements, the information provided by the script should be identified with functional text that can be read by assistive technology.

    • If hidden content is exposed with scripting event handlers, equivalents should be available without scripting or event handlers should be triggered with the keyboard.
    • One way to check compliance on this standard is to be sure essential information is not lost when scripting functions are turned off.
  13. §1194.22 (m) Specify Accessible Applets and Plug-ins

    When a web page requires that an applet, plug-in or other application be present on the client system to interpret page content, the page must provide a link to a plug-in or applet that complies with §1194.21 (a) through (l).

    • Applets and plug-ins must satisfy the Section 508 software standards. In particular, they must be completely usable without a mouse.
    • Applets and plug-ins should be fully tested using only the keyboard.
    • Applets, scripts and plug-ins and the content within them should be accessible to assistive technologies, or else an alternative means of accessing equivalent content should be provided.
    • A link should be provided to a disability-accessible page where the plug-in can be downloaded.
  14. §1194.22 (n) Design Accessible Forms

    When electronic forms are designed to be completed online, the form shall allow people using assistive technology to access the information, field elements, and functionality required for completion and submission of the form, including all directions and cues.

    • Form elements should be carefully labeled, placing the text labels close to the controls.
    • Scripting of form elements should not interfere with assistive technologies or keyboard.
    • Form input elements should have label elements associated with them in the markup or are given a descriptive title attribute.
  15. §1194.22 (o) Offer Skip Navigation

    A method shall be provided that permits users to skip repetitive navigation links.

    • A method for users to skip over navigation links should be provided. This can be accomplished with a "skip navigation" link at the top of each page.
  16. §1194.22 (p) Alert Users to Timed Responses

    When a timed response is required, the user shall be alerted and given sufficient time to indicate more time is required.

    • If a response is expected from a user in a certain prescribed time, the user should be alerted to that fact and additional time should be offered as an option.
  17. §1194.22 (ref) Reference Source Files
    • All source files (documents) that are embedded on or linked from a page must be compliant. Examples of source documents include PDFs, Word documents, and Excel spreadsheets.

For More Information

NCI staff can also access more detailed information about Accessibility on the NCI Intranet. For information about NCI's continuing efforts to make its Web-based products accessible to all users or to report an accessibility problem on any NCI site, please e-mail us at nci508@mail.nih.gov.

  • Updated: May 3, 2012