"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. "all" uses all data associated with flagged and unflagged visibilties. The default uses only unflagged (good) data.