Toshiba GD-1200 Operator's Manual page 169

Duplex printing direction differs depending on the received original size.
1. Received LD, LG, LT, A3, A4, or B4-sized originals are printed so that they can be bound along the long edge
of direction.
2. Received ST, A5 or B5-sized originals are printed so that they can be bound along the short edge of direction.
( 1 ) ( 2 )
C C
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