以下常量由本扩展模块定义，因此只有在本扩展模块被编译到 PHP 中，或者在运行时被动态加载后才有效。
| Constant | Description |
|---|---|
| FAMChanged (integer) | Some value which can be obtained with fstat(1) changed for a file or directory. |
| FAMDeleted (integer) | A file or directory was deleted or renamed. |
| FAMStartExecuting (integer) | An executable file started executing. |
| FAMStopExecuting (integer) | An executable file that was running finished. |
| FAMCreated (integer) | A file was created in a directory. |
| FAMMoved (integer) | This event never occurs. |
| FAMAcknowledge (integer) | An event in response to fam_cancel_monitor(). |
| FAMExists (integer) | An event upon request to monitor a file or directory. When a directory is monitored, an event for that directory and every file contained in that directory is issued. |
| FAMEndExist (integer) | Event after the last FAMEExists event. |