Answer
ArcMap was designed so that the layout would use the paper size and orientation setup of the intended printer. This is accomplished by setting the printer, paper size and orientation and then checking the 'Use Printer Paper Settings' (or 'Same as Printer at 8.x) in the ArcMap Page and Print Setup dialog box (known as Page Setup in 8.x). When the map document is saved, ArcMap saves this information to the map document.
Note:
ArcMap stores the Windows printer sharename in the map document; for example, if the printer sharename is 'designjet' and the printer server name is 'printerserver', then the name stored in the map document is '\\printerserver\designjet'.
With the ArcGIS 8.x versions, an error would occur for three reasons:
· The original printer used to create the page size settings was no longer available.
· The name of the printer had changed.
· The printer driver has been changed or updated.
At 9.x, this process was improved. ArcMap will turn off Use Printer Paper Setting and open the map without modifying the map page size as a result of one of the above conditions. The map document will lose its printer paper size setting, but the map will not change size or scale.
If Use Printer Paper Settings is not used, then the printer paper size and orientation will need to be set to a slightly larger size than the actual map page size and orientation. This is because ArcMap will draw the map inside the minimum required margins of the printer paper size and orientation selected.