leftMargin (USHORT)
The value in this field defines the left unprintable area for this input. The left margin is defined as that area to the left of the first printable character in a line written in the marking direction. The units for this value are specified by lengthUnits in the PRTDEVCHAR data structure. A value of hex 'FFFF' indicates that the printer does not have, nor can it determine, this value.
Note: This value specifies the limitation of the printing mechanism and also indicates that particular interpreters may place additional limitations on the margins.