xfig starts the graphics device driver for producing XFig
  (version 3.2) graphics.  The auxiliary function ps.options can be used to set and view
  (if called without arguments) default values for the arguments to
  xfig and postscript.
xfig(file = if(onefile) "Rplots.fig" else "Rplot%03d.fig", onefile = FALSE, encoding = "none", paper = "default", horizontal = TRUE, width = 0, height = 0, family = "Helvetica", pointsize = 12, bg = "transparent", fg = "black", pagecentre = TRUE, defaultfont = FALSE, textspecial = FALSE)onefile = FALSE give a C integer format such as
    "Rplot%03d.fig" (the default in that case).
    (See postscript for further details.)
  iconv: in a Western UTF-8 locale you probably want to
    select an 8-bit encoding such as latin1, and in an East Asian
    locale an EUC encoding.  If re-encoding fails, the text
    strings will be written in the current encoding with a warning."A4", "Letter" and "Legal" (and these
    can be lowercase).  A further choice is "default", which
    is the default.  If this is selected, the papersize is taken
    from the option "papersize" if that is set to a non-empty
    value, otherwise "A4".postscript for further details.)"AvantGarde", "Bookman", "Courier",
    "Helvetica" (the default), "Helvetica-Narrow",
    "NewCenturySchoolbook", "Palatino" or
    "Times".  Any other value is replaced by
    "Helvetica", with a warning.xfig can produce multiple plots in one file, the XFig
  format does not say how to separate or view them.  So
  onefile = FALSE is the default.  The file argument is interpreted as a C integer format as used
  by sprintf, with integer argument the page number.
  The default gives files Rplot001.fig, ..., Rplot999.fig,
  Rplot1000.fig, ....
  Line widths as controlled by par(lwd =) are in multiples of
  5/6*1/72 inch.  Multiples less than 1 are allowed.  pch = "." with
  cex = 1 corresponds to a square of side 1/72 inch.
Windows users can make use of WinFIG (http://www.schmidt-web-berlin.de/WinFIG.htm, shareware), or XFig under Cygwin.
Devices,
  postscript,
  ps.options.