&define_field_saving
filename = "gunRun.fsave",
time_interval = 1e-9,
double start_time = 5e-9
&end
This command results in saving of the fields at 1ns intervals starting
at simulated time of 5ns to file "gunRun.fsave". Successive saves are
placed in successive SDDS pages.
&define_field_saving
STRING filename = NULL;
double time_interval = 0;
double start_time = 0;
long save_before_exiting = 0;
&end