What does the number on the printer(ink) cartridge mean?

I need to buy new ink for my printer, so I was wodering what the number on the cartride meant. like the 22 in this picture...








http://cdn.overstock.com/images/products/etilize/images/300/11200715.jpgWhat does the number on the printer(ink) cartridge mean?
It is a reference number that HP (and all the other printer manufactures) use to identify their cartridges.





They usually have two numbers, a part number and a short name.





Short Name for yours is the HP 22 Color, while the part number is C9352AN.





That is just how they do it, who knows why.What does the number on the printer(ink) cartridge mean?
i believe its just the number to distinguish the type of cartridge dependant on the model of your printer. There maybe several printers that can take cartridge number 22.
I think he is right, it's like a serial number so you can use that when you order the refills.