What is the difference between IPCL and HPGL2?

[Collin Day]

Does anyone know the difference between the following:

@PJL ENTER LANGUAGE = IPCL

and

@PJL ENTER LANGUAGE = HPGL2

I am confused.  Using the DDK, I made a ppd from the following driver file, trying to understand how the PCL3 GUI language works.

#include <font.defs>
#include <media.defs>
#include <raster.defs>
#include <pcl.h>

DriverType pcl

ModelNumber ($PCL_PAPER_SIZE $PCL_RASTER_END_COLOR $PCL_RASTER_CRD $PCL_PJL $PCL_PJL_PCL3GUI)

Font *
Manufacturer "HP"
Version "1.0"

Filter application/vnd.cups-raw 50 rastertopclx

HWMargins 18 12 18 12
*MediaSize Letter

ColorModel Gray k chunky 10

// Supported input slots
*InputSlot 7 "Auto/Automatic Selection"
InputSlot 2 "Manual/Tray 1 - Manual Feed"
InputSlot 4 "Upper/Tray 1"
InputSlot 1 "Lower/Tray 2"
InputSlot 5 "LargeCapacity/Tray 3"

// Supported resolutions
*Resolution - 8 0 0 0 "600dpi/600 DPI"

Throughput 10
ModelName "HP PhotoSmart Pro B8850"
PCFileName "hp-b8850-test.ppd"

Then, I went to ImageAlchemy and took a small jpeg and had it converted to pcl, hp photosmart, hp-rtl(designjet), and hp-rtl(paintjet).

I have a photosmart pro b8850 printer, so it uses pcl3 gui - which in turn uses the hp-rtl language, and is supported by the driver provided by the ddk.  I was able to get the pcl file to print (expected), the paintjet and designjet rtl files to print using lp -d printer file -oraw and my test ppd, but the lp -d printer photosmart.prn won't print (lp: Unsupported format 'application/octet-stream'!) and prints garbage when -oraw is added.

ipcl is not the same as pcl or pcl3 gui (hpgl2 or rtl), but it is (I thought) for photosmart printers which I have.  Could someone help clear this up a bit for me since I can't find any useful info anywhere on the web?  I am currently assuming that pcl3 gui uses the @PJL ENTER LANGUAGE = HPGL2
command and I should use this to effectively use my printer, but I am wondering if I am wrong and should do something different?

Sorry for all the posts to this and the development forum - this is all pretty confusing to someone who just tried to "pick this all up" without a lot of printer driver experience.

Thanks again!