IAccessible2 is an

accessibility Accessibility is the design of products, devices, services, vehicles, or environments so as to be usable by people with disabilities. The concept of accessible design and practice of accessible development ensures both "direct access" (i. ...

API for

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

applications. Initially developed by IBM under the codename Project Missouri, IAccessible2 has been placed under the aegis of the Free Standards Group, now part of the

Linux Foundation The Linux Foundation (LF) is a non-profit technology consortium founded in 2000 as a merger between Open Source Development Labs and the Free Standards Group to standardize Linux, support its growth, and promote its commercial adoption. Addi ...

. It has been positioned as an alternative to Microsoft's new UI Automation API. While UI Automation is trumpeted as "royalty-free", IAccessible2 claims to be an "open standard".

Goals

Whereas UI Automation marks a radical break from Microsoft Active Accessibility (MSAA) to create a more flexible accessibility API, IAccessible2 fills in perceived omissions in MSAA to match the Java Accessibility API and

Assistive Technology Service Provider Interface Assistive Technology Service Provider Interface (AT-SPI) is a platform-neutral framework for providing bi-directional communication between assistive technologies (AT) and applications. It is the ''de facto'' standard for providing accessibility ...

(AT-SPI). By extending the MSAA interface, rather than replacing it, IAccessible2 allows "application developers to leverage their investment in MSAA while also providing an Assistive Technology (AT) access to rich document applications." It is also advantageous for Microsoft's commercial competitors, Sun and IBM, to promote an alternative accessibility interface to the Windows platform standard, which explains both their focus on developing non-MSAA/UIA interfaces and their promotion of cross-platform support despite the lack of any AT that is cross-platform that might use it. Project Missouri was started when the

State of Massachusetts Massachusetts (Massachusett: ''Muhsachuweesut Massachusett_writing_systems.html" ;"title="nowiki/> məhswatʃəwiːsət.html" ;"title="Massachusett writing systems">məhswatʃəwiːsət">Massachusett writing systems">məhswatʃəwiːsət'' En ...

, in the process of adopting the OpenDocument format for its public records, required that the format be made accessible. Increasing the accessibility of dynamic web applications, for example by exposing custom controls for use with

assistive technology Assistive technology (AT) is a term for assistive, adaptive, and rehabilitative devices for Disability, people with disabilities and the elderly. Disabled people often have difficulty performing activities of daily living (ADLs) independently, ...

and by filtering streams of new information by type and importance, became a second major focus for the project.

Support

Support for IAccessible is present in

LibreOffice LibreOffice () is a free and open-source office productivity software suite, a project of The Document Foundation (TDF). It was forked in 2010 from OpenOffice.org, an open-sourced version of the earlier StarOffice. The LibreOffice suite co ...

as of version 4.2. It is in development for

Apache OpenOffice Apache OpenOffice (AOO) is an open-source office productivity software suite. It is one of the successor projects of OpenOffice.org and the designated successor of IBM Lotus Symphony. It is a close cousin of LibreOffice, Collabora Online and ...

Mozilla Application Suite The Mozilla Application Suite (originally known as Mozilla, marketed as the Mozilla Suite) is a discontinued cross-platform integrated Internet suite. Its development was initiated by Netscape Communications Corporation, before their acquisition ...

NonVisual Desktop Access NonVisual Desktop Access (NVDA) is a free and open-source, portable screen reader for Microsoft Windows. The project was started by Michael Curran in 2006. NVDA is programmed in Python. It currently works exclusively with accessibility APIs su ...

and the

Opera Opera is a form of theatre in which music is a fundamental component and dramatic roles are taken by singers. Such a "work" (the literal translation of the Italian word "opera") is typically a collaboration between a composer and a libr ...

web browser. Although IAccessible2 was introduced as a Windows accessibility API, Qt Development Frameworks is treating IAccessible2 as a potential alternative to

AT-SPI Assistive Technology Service Provider Interface (AT-SPI) is a platform-neutral framework for providing bi-directional communication between assistive technologies (AT) and applications. It is the ''de facto'' standard for providing accessibility ...

on Linux too, and planning to add preliminary support to Qt 4.3. As of 2019, Qt uses MSAA and IAccessible2 on Windows, and continues to use AT-SPI for Unix/X11 systems.Qt documentation
(2019), accessed 2020-11-08.

References

Accessibility API Windows APIs