  plsfnam(fnam)
  *************

  plsfnam

  Sets the current output file name, if applicable. If the file name has
  not been specified and is required by the driver, the user will be prompted
  for it. If using the X-windows output driver, this sets the display name.
  This routine, if used, must be called before initializing PLplot.

  fnam (char *, input): Pointer to file name string.

