# Automation user defined functions Reference

Below is a complete list of the user defined functions available in AutoIt. Click on a user defined function name for a detailed description.

When using them you need to add a #include <WinAPISys.au3>.

User Defined Function | Description
--- | ---
_WinAPI_CallNextHookEx | Passes the hook information to the next hook procedure in the current hook chain
_WinAPI_SetWindowsHookEx | Installs an application-defined hook procedure into a hook chain
_WinAPI_SetWinEventHook | Sets an event hook function for a range of events
_WinAPI_UnhookWindowsHookEx | Removes a hook procedure installed in a hook chain by the _WinAPI_SetWindowsHookEx function
_WinAPI_UnhookWinEvent | Removes an event hook function