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

EN SC, Scale 19-43
Figure 19-18Isotropic Scaling
z Left, Bottom — Positions the isotropic area in the P1/P2 limits.
(These parameters are always specified together and are valid for
isotropic scaling only.) The left parameter indicates the
percentage of the unused space on the left of the isotropic area;
the bottom parameter indicates the percentage of unused space
below.
• The defaults for the left and bottom parameters are each 50%.
This centers the isotropic area on the page with the unused
space equally divided between left and right or top and bottom,
as shown in the previous illustrations.