HP PCL 5 Reference Manual page 69

Figure 4-6 Cursor Moves at Different Unit of Measure Settings
The printer's physical dot size has no direct bearing on the size of
PCL Units used in cursor movements. In addition, PCL Units are not
affected by the current control panel or PJL resolution setting.
Note If no other unit of measure value has been specified, then the default
is one Unit equals 1/300 inch. In this case, a cursor movement of
450 Units moves the cursor 1.5 inches, whether printed at 300 or
600 dpi print resolution.
EN
Unit of Measure Command 4-15