Each custom router must implement the IRouter interface. When a file is submitted to the records repository, Office SharePoint Server 2007 calls the appropriate custom router, if there is one, by using the OnSubmitFile method.
The fileToSubmit, properties, destination, and resultData parameters are passed by reference, so that the custom router can change these values as necessary. Therefore, the custom router has the ability to edit the submitted document and its associated metadata, change the storage destination of the document, and communicate details of its processing to the records repository.