| 
	    plgcolbg
	  ( | r, | 
| g, | |
| b ); | 
Returns the background color (cmap0[0]) by 8-bit RGB value.
r
	  (PLINT_NC_SCALARReturned value of the red intensity in the range from 0 to 255.
g
	  (PLINT_NC_SCALARReturned value of the green intensity in the range from 0 to 255.
b
	  (PLINT_NC_SCALARReturned value of the blue intensity in the range from 0 to 255.
      Redacted form: plgcolbg(r, g, b)
    
This function is used in example 31.