expression.MirrorMargins
expression Required. An expression that returns a PageSetup object.
Remarks
If the MirrorMargins property is set to True, the LeftMargin property controls the setting for inside margins and the RightMargin property controls the setting for outside margins.
Example
This example sets the inside margins of the active document to 1 inch (72 points) and the outside margins to 0.5 inch. The InchesToPoints method is used to convert inches to points.
With ActiveDocument.PageSetup
.MirrorMargins = True
.LeftMargin = 72
.RightMargin = InchesToPoints(0.5)
End With