io_arg

A path, or writable text stream (as returned by fopen);

An instance of the RTreeStyle class describing the fill colour and stroke width and colour for each level of the tree.

The axis to which the extent variable is to be applied, one of "height" or "width" (default "width");

The size of the output plot on the specified axis in units of PostScript point, 1/72 inch, (default 216 is 3 inches);

Extra space around the plot in units of PostScript point, (default 0).

See also: RTreeStyle