The object x represents a matching found between
  two point patterns X and Y. The matching may be
  incomplete. See pppmatching.object for further
  description.
This function plots the matching by drawing the two point patterns
  X and Y as red and blue dots respectively, and drawing
  line segments between each pair of matched points. The width of the
  line segments is proportional to the strength of matching. The
  proportionality constant can be adjusted using the argument
  adjust.
Additional graphics arguments … control the
  plotting of the window (and are passed to plot.owin)
  and the plotting of the line segments 
  (and are passed to plot.psp, plot.linim
  and ultimately to the base graphics function
  polygon).
The argument addmatch is for use mainly by developers to
  study algorithms which update the matching.
  If addmatch is given, it should be a matrix with dimensions
  npoints(X) * npoints(Y). If addmatch[i,j] > 0 then
  a light grey line segment will be drawn between X[i] and Y[j.