5-2.2 General Requirements

Accessibility is accomplished by designing software that accommodates the widest range of users, including those with disabilities. Listed below are some general requirements that will help the Postal Service ensure that Web–based applications and information remain accessible:

• The Postal Service will take advantage of operating system and Web client built–in accessibility features when those features are available to both end users and software developers.
• The Postal Service will maintain standards for the following accessibility aids or assistive technologies that are used by people with disabilities to access Web–based applications and information:
• Screen magnifiers: Help visually impaired people by allowing them to enlarge any part of the screen (i.e., as with a magnifying glass).
• Screen readers: Help blind people by making on–screen information available as synthesized speech or for display as refreshable Braille.
• Voice input aids: Help mobility– or dexterity–impaired people by allowing them to control the computer with their voice instead of with a mouse or keyboard.
• On–screen keyboards: Help people who are unable to use a standard keyboard by providing an on–screen keyboard that can be used with a pointing device.
• Keyboard filters: Help people who have trouble typing by compensating for erratic motion, tremors, or slow response time.
• Alternative input devices: Help people who would prefer to control their computer with a device other than a keyboard or mouse.
• The Postal Service will develop Web–based applications that are based on interoperable specifications and do not interfere with accessibility features installed and activated by a user (e.g., operating system features and Web client capabilities, as well as installed accessibility aids). Web–based developers should do the following:
• Support native operating system and activated accessibility features for major operating systems that are integrated with input and output devices (e.g., keyboard, sound, display, or mouse). These features are supported by most Web clients and Web browsers. Developers should be aware of how these features will be used in combination with Web–based technologies. Standards for each operating system related to each specific requirement are shown in the “References” area under each specific requirement in Chapter 5 of Handbook AS–508–A, Section 508 Technical Reference Guide, Software Applications and Operating Systems.
• Use standard markup tags in creating Web content where possible (i.e., use the W3C recommendations). Standardized markup is often already supported by Web clients and operating system accessibility features. Using these tags will often eliminate the need for software to provide explicit accessibility support.
• Use caution when using plug–ins or enhancing Web content, because accessibility aids may have difficulty identifying them (i.e., accessibility aids require specific information to work successfully with screen elements). When custom or enhanced Web content is used, developers must use appropriate methods to allow Web content and information (e.g., providing alternate or equivalent content) to function with accessibility aids. The nonproprietary information that is created using standard HTML, XHTML, XML, or SGML allows for access using multiple clients (tools), reduces development costs, and permits the interoperability of technologies unknown by the author or creator of the information. Provide flexibility by allowing for a variety of input (e.g., keyboard, mouse) and output (e.g., color, sound, images, text) methods.
• Allow accessibility aids and nonstandard clients to use and configure the Web applications and information automatically. For example, detecting a specific browser and providing additional modification of Web content should not prevent unknown clients and accessibility aids from accessing the content.

Handbook AS–885, usps.com Development Process and Standards, provides processes and standards for building and maintaining an information presence or application on usps.com and defines the design and development standards and best practices for use on that site. It may be accessed online at http://blue.usps.gov/cpim/ftp/hand/as885.pdf.