The MicrosoftÒ WindowsÔ 3.1 operating system is a single-user system for personal computers. Applications that run with this operating system use functions in the Windows applications programming interface (API). This manual describes the API functions in alphabetic order, including each function's purpose, the version of Windows in which it first appeared, and the function's syntax, parameters, and possible return values. Many function descriptions also contain additional information and simple code examples that illustrate how the function can be used to carry out simple tasks.