Epson Stylus Pro 7800 User Manual page 58

This function is effective only when the print data length is shorter
than the printable width of the roll paper. The print data will
automatically be turned 90 degrees to print crosswise, saving roll
paper.
Original
To enable this function, follow the steps below.
1. Select Auto Rotate. The Roll Width button is activated.
2. Click Roll Width. The Roll Paper Width dialog box appears.
3. Select the installed roll paper size from the pull-down menu.
4. Click OK.
Print Page Line
This function lets you specify whether to print a page line on the
right side, and also below the document for manual cutting. To
enable this function, select Print Page Line.
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Printing with Windows
Auto Rotate off Auto Rotate on