2PLOT: plot frame - draw a frame

Usage: plot frame [xtext=<xtext>] [ytext=<ytext>] [tics=<ticaxes>]
                  [labels=<labelaxes>] [grid] [zero]

draws a rectangular frame with corners (X0,Y0), (X1,Y0), (X1,Y1) and
(X0,Y1). Subsequently produced graphics is clipped on the borders of 
the frame. The x- and y-axes are labeled with the titles xtext and 
ytext, respectively. The parameter tics and labels determines whether 
tics and numeric labels are drawn. The possible values for ticaxes and 
labelaxes are:

  off     No labels or tics.
  x       Labels or tics only on the x-axis.
  y       Labels or tics only on the y-axis.
  x,y     Label or tics on both axes (default).

If the option grid is present, a fine grid is drawn. If the option
zero is present, fine lines will be drawn along x=0 and y=0 (if they 
fall within the frame).