"dtime" If the x-axis is "time", plot the time in fractions of a day. The default is to plot in hh:mm:ss. "compress" If the variable is a 2D array of values, average the variables along the second dimension. "overlay" By default, when a variable takes on several values, each is plotted on a separate plot. The overlay option makes a single plot. "unwrap" Unwrap the phases on the yaxis variable. Cannot unwrap an xaxis variable. By default phases are not unwrapped.