Oki ML5521 User Manual page 8

Controlling Access to the Printer
> You can control access to the printer by changing the setting
for the Operator Panel Function in the Menu from Full
Operation (the factory default) to Limited Operation.
> When Limited Operation is selected, the PRINT QUALITY and
CHARACTER PITCH keys don't work. This prevents these
settings from being changed from the control panel when
several people are using the printer.
For more information, see "Changing the Menu Settings" in "Using your
Printer".
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