Scantron OpScan 4ES Operator's Manual page 80

Chapter 4: Scanner Modes
Scantron Score Emulation Mode
60
2. Note the location of the cartridge holder inside the
printer assembly. Also note the ruler, printer
alignment mark, and thumbscrew that sits beside
the cartridge holder. These are the elements used
to position the printer.
Scantron OpScan 4ES and NSIGHT 4ES Scanners