Set the device used for plots.
XSPEC> setplot device <PGPLOT device> or NONE
where <PGPLOT device> is a string that gives an (optional) file name
and device plot type (see below and the PGPLOT documentation for options
available). Entering the device none will close the current plot device
and disable plotting until a subsequent setplot device is issued. Note
that if an environment (UNIX) or logical (VMS) variable called
PGPLOT_TYPE exists, then XSPEC automatically sets it as the plot device on
invocation.