The following information is provided as is, and the authors take no responsibility for the correctness.
Part of PPA - HP Printing Performance Architecture, a proprietary set of protocols developed by Hewlett Packard for a short-lived series of DeskJet printers.
HP Sleek Control Protocol (SCP) is a control protocol which sends command sequences to tell the printer to do things like load a sheet of paper, eject and print a sweep.