This value has one purpose only: When you set the page orientation
to Automatic
in the Print dialog, the output engine decides by
means of the format width, if the output should be rotated or not.
(When typesetting with TIF Print and TIFF Spooler you should define
the maximum possible film width here to avoid large format output in
landscape orientation!) The value is set in the page measurement unit
(this means inches by default).
