HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part II

EN Using the Scale Command 19-5
For example, to divide the X-axis into 12 units, and the Y-axis into
10 units, specify the X-axis to scale from 0 to 12, and the Y-axis to
scale from 0 to 10. P1 becomes the origin with user-unit coordinate
(0,0) and P2 becomes (12,10). The entire plotting area is now divided
into the desired units. Subsequent plotting commands use these units
(see Figure 19-1). If you command the printer to move to the point
(3,4), the printer moves to the location equivalent to (3,4) user-units
(not (3,4) plotter units).
Figure 19-1 User-Unit Scaling with Default P1 and P2
If you move the locations of P1 and P2, the size of the user-units
changes. Assume that the previous illustration showed P1 and P2
in their default locations (the lower-left and upper-right corners,
respectively, of the PCL Picture Frame). In Figure 19-2, P1 and P2
have the same user-unit values (set with the Scale command [SC]),
but their physical locations have been changed (using Input P1 and
P2 [IP]). Note that the size of the user-units decreased.