Printek 4000se Operator's Manual page 61

P R I N T E R C O N F I G U R A T I O N
Unidirectional
Unidirectional Printing
No
Possible Values: No*, Yes
This item selects unidirectional printing instead of bi-directional printing.
This may be used to improve the straightness of vertical lines for critical
applications such as printing small bar codes.
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