HP 1055CMHP - Manual (Page 297)

Functional Overview
10-11 HP DesignJets 1050C and 1055CM Printers Service Manual
Snout Wiper
Snout wiper is used to clean the ink accumulation that happens on
the snout of the pen (vertical corner on the interconnect side)
because of wiping operation. This is done to avoid spreading this
ink over the interconnect when replacing the pen and generating ink
shorts between interconnect pads.
Handle and Printable Label
The handle is used to remove and install the PHC. Also, the printer
uses the handle top surface to print and scan some patterns in order
to recognize if:
n PHC is present or not.
n PHC is new or has been used previously.
In addition, there is a built-in mark on the handle (a vertical hole) to
calibrate the service station (Scan-axis) if there is a problem and the
EEROM is erased.