obviously this attribute is managed by a client. The point is that the ADF files may benefit interoperability between clients. There is another attribute, "upload",  that is undocumented because they are only of interest to a specific client (who needs to track what uploads are pending). But the "local" attribute I think is of interest to all clients who may need to process an ADF file. If you move the file around then obviously this attribute may become outdated. The client may or may not offer a way to update an ADF file with a new local location. I don't think we should mandate this.