| 
	    plgvpw
	  ( | p_xmin, | 
| p_xmax, | |
| p_ymin, | |
| p_ymax ); | 
Get viewport limits in world coordinates.
p_xmin
	  (PLFLT_NC_SCALARReturned value of the lower viewport limit of the world coordinate in x.
p_xmax
	  (PLFLT_NC_SCALARReturned value of the upper viewport limit of the world coordinate in x.
p_ymin
	  (PLFLT_NC_SCALARReturned value of the lower viewport limit of the world coordinate in y.
p_ymax
	  (PLFLT_NC_SCALARReturned value of the upper viewport limit of the world coordinate in y.
Redacted form:
	    General: plgvpw(p_xmin, p_xmax, p_ymin, p_ymax)
	  
This function is used in example 31.