# FilesystemChangeData

A [script add-in](../../../scripting/script_add-ins) can monitor file and folder changes by implementing the [**OnFilesystemChange**](../scripting_events/onfilesystemchange) event and calling the [**FSUtil**](fsutil)**.WatchChanges** method to establish monitoring.

| Property Name | Return Type | Description                                                                                                                                                                |
| ------------- | ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| id            | _string_    | Returns the ID of the watcher that detected a file or folder change. This ID is assigned when you create the watcher in the call to [**FSUtil**](fsutil)**.WatchChanges**. |
