A guiding standard

The effectiveness of screen readers depends on an application's underlying

programming. Since 1997, Microsoft Corp. has incorporated a developer technology

called Microsoft Active Accessibility (MSAA) into many of its programs

and several operating systems, including Office 97, Office 2000, Windows

98, Windows 2000 and Internet Explorer 3.0, 4.01 and 5.0.

MSAA allows accessibility aids such as screen readers to obtain information

about user interface elements and for programs to expose that information

to the screen readers. For example, MSAA supplies the type of object, name

of the object, location of the object, current state of the object, navigation

information and notification of changes in the user interface.

Screen reader programs and other aids do not have to rely on MSAA. Developers

can opt to write their own proprietary scripts instead of following Microsoft's

standard, or they can use a combination of proprietary scripts and MSAA.

Vendors that follow MSAA have the advantages that come along with using

a standard, such as compatibility. Vendors that use proprietary scripts,

however, are not limited by the standard and can make the programs more

robust.