FLASH4 outputs the runtime parameters of a simulation to all checkpoint files. When a simulation is restarted, these values are known by the RuntimeParameters unit while the code is running. On a restart, all values from the checkpoint used in the restart are stored as previous values in the lists kept by the RuntimeParameters unit. All current values are taken from the defaults used by FLASH4 and any simulation parameter files (e.g., flash.par). If needed, the previous values from the checkpoint file can be obtained using the routines RuntimeParameters_getPrev.