Following are the hook functions:
| Function | Description |
| CallMsgFilter | Passes a message and other data to the filter function for the current message. |
| CallNextHookEx | Passes hook information down the hook chain. |
| DefHookProc | Calls the next filter function in a filter-function chain. |
| SetWindowsHookEx | Installs a system filter function, an application filter function, or both. |
| UnhookWindowsHookEx | Removes a Windows filter function from a filter-function chain. |
For detailed information about the hook functions, see the Microsoft Windows Programmer's Reference, Volume 2.