//SETOPTION, NO-AUTO-MARGINS
When specified, this option disables the automatic 1/4" margin adjustment applied by the //SETFONT directive when calculating the character width from a negative width parameter—i.e. from the number of characters to fit in the width of the page. This automatic adjustment was added years ago in conjunction with the APEX auto-margin adjustment, on the theory that even if the printer doesn't report a physical margin, at some point you may want to print to paper, where the margin would most likely need to be applied. So it seems better to be calculate the font width so as to be compatible with physical printing.
There are situations however where this doesn't make sense and in fact causes problems. One would be when using //SETFONT with a negative width parameter to come up with an appropriate font size to match up to a form generated from an image scaled to the page. In that case, you probably want the width basis used for the font calculation to be the same as used for the image scaling, i.e. without any automatic margin offsets.
