MSAA was originally made available in April 1997 as part of the Microsoft Active Accessibility Software Developers Kit (SDK) version 1.0. The SDK packaged included documentation, programming libraries, sample source code, and a Re-Distributable Kit (RDK) for accessible technology vendors to include with their products. The RDK included updated operating system components for Microsoft Windows 95. Since Windows 98 and Windows NT 4.0 Service Pack 4, MSAA has been built-into all versions of the Windows platform, and has received periodic upgrades and patches over time.