Several errors fall into this category; the action to be taken depends on conditions that are unique to each program. For example, a program that has no means of recovering data that is lost on its way to an LU can decide that the LU has to revert to some earlier point in communications or inquiry (might have to reenter its inquiry), and sends a request to that effect. The LU can then reenter its request and start the process at an initial stage. On the other hand, a program can always keep a copy of its latest transmission to an LU so that it can retransmit it, if required.