Epson TM-C3400BK Technical Reference Manual page 182

Print Preview
If this function is checked, the print preview window is displayed when printing is performed from
an application, allowing you to check the print result image before printing.
Displays the print preview before printing if this check box is turned on.
To improve 2D symbol scanning accuracy, we recommend no paper feed during 2D symbol
printing.
The following items can be set in [Display Media Feed Position].
Display Media Feed
Position
182
Setting
Display Print Preview
Print Media Feed Position
Specification
Displays the media feed position on the print
preview window. The default is set as "Display".
Prints the media feed position.
The default setting is set as "Not print".
Paper feed position
With paper feed