CHAPTER 3 PCL5C - 9 
♣  Black reference for value #1, #2, #3 
♣  This mode specifies the black value (the highest level of density). 
♣  Each value indicates a color as follows; 
#1: red 
#2: green 
#3: blue 
Range: -32767 ~ 32767 
  When the encoding mode is 2 or 3, this setting is valid. 
 
 
2.3.  Using HP-GL/2 Color Mode 
Two methods are provided to set the color mode in the HP-GL/2 mode.    Set the color mode by the PCL 
command, then transfer to the HP-GL/2 mode.    Execute the NP command. 
For the details on how to use the color selections in the HP-GL/2 mode, refer to Section 6 'HP-GL/2'.