The filename must contain the full path of an RID file. This file is automatically created by dbmlsync after the first synchronization.
It uses the same location and name as the database file. For UltraLite databases, filename should be the same as the database name.
When applying the -r option, the $remote_id action variable can be used in message handlers to reference the remote ID in
the RID file. By default, Remote IDs are GUIDs.
Use the -r option multiple times to identify multiple databases.