Sometimes it is desirable to store all files needed for software update at a central place and have the devices get the files on their own time and pace. In this case the Client would tell the Server only the location of the file. Then the actual transfer is initiated by the device.
There is no specific support for this use case in this specification. However, it is possible to use the described mechanisms to transfer a file that does not contain the actual software but the location of the external source(s) where the software file(s) should be pulled from.