Most of the plots of interferometric data in
are handled by one
procedure (plotdata). Consequently, there is one widget handling
the plot selection (ww_plot). Whenever a plot is requested, a
selection widget designed for that class of plot (point, scan, astrom,
etc.) is opened, replacing any currently displayed selection widgets from
previous requests. A second widget is created for the selection of which
indices to plot, if this input is required. Plots can be 2-dimensional
or 3-dimensional. Therefore, three data streams (`x', `y',
and `z') are available.