These new printer init commands effect minor horizontal and vertical adjustments to the overall positioning of everything on the page, except images:
XOFFSET = ###
YOFFSET = ###
The units are twips (1440 to the inch), with positive values shifting the output down and to the right, negative up and to the left.
The concept here is to make it easier to adjust the output of existing reports designed for plain or pre-printed forms, to instead use scanned, printed-as-you-go forms. Often this presents difficulties in getting the text to line up with the form due to minor fluctuations in the size of the form image introduced by scanning or scaling to print.
Note that the TMARGIN and LMARGIN commands are not very useful for this kind of thing, partly because they operation in such coarse units, partly because they have other side effects, and partly because they don't affect X,Y coordinate positioning (in GDI directives). The XOFFSET and YOFFSET parameters were designed to overcome these issues and should be used instead.