| x0
	  (PLFLT, input)            World X coordinate of origin.
	  y0
	  (PLFLT, input)            World Y coordinate of origin.
	  xopt
	  (const char *, input)	    Pointer to character string specifying options for horizontal
	    axis.  The string can include any combination of the following
	    letters (upper or lower case) in any order:
	     		  a: Draws axis, X-axis is horizontal
		  line (y=0), and Y-axis is vertical
		  line (x=0).
				  b: Draws bottom (X) or left (Y) edge
		  of frame.
				  c: Draws top (X) or right (Y) edge of
		  frame.
				  f:  Always use fixed point numeric labels.
				  g: Draws a grid at the major tick
		  interval.
				  h: Draws a grid at the minor tick
		  interval.
				  i: Inverts tick marks, so they are
		  drawn outwards, rather than inwards.
				  l: Labels axis logarithmically.  This
		  only affects the labels, not the data, and so it is
		  necessary to compute the logarithms of data points before
		  passing them to any of the drawing routines.
				  m: Writes numeric labels at major tick
		  intervals in the unconventional location (above box for
		  X, right of box for Y).
				  n: Writes numeric labels at major tick
		  intervals in the conventional location (below box for X,
		  left of box for Y).
				  s: Enables subticks between major
		  ticks, only valid if t is also
		  specified.
				  t: Draws major ticks.
		
xtick
	  (PLFLT, input)	    World coordinate interval between major ticks on the x axis.
	    If it is set to zero, PLplot automatically generates a suitable
	    tick interval.
	  nxsub
	  (PLINT, input)	    Number of subintervals between major x axis ticks for minor
	    ticks.  If it is set to zero, PLplot automatically generates a
	    suitable minor tick interval.
	  yopt
	  (const char *, input)	    Pointer to character string specifying options for vertical
	    axis.  The string can include any combination of the letters
	    defined above for
	    xopt, and in addition
	    may contain:
	    ytick
	  (PLFLT, input)	    World coordinate interval between major ticks on the y axis.
	    If it is set to zero, PLplot automatically generates a suitable
	    tick interval.
	  nysub
	  (PLINT, input)	    Number of subintervals between major y axis ticks for minor
	    ticks.  If it is set to zero, PLplot automatically generates a
	    suitable minor tick interval.
	  
 |