Side 1 is the surface of the paper printed during one-sided printing, or the surface of the first print during duplex printing.
Side 2 is the surface of the paper printed after side 1 has been printed during duplex printing.
Single-sided printing: Printed side face down
A. Side 1
B. Paper feed direction of Side 1
Duplex printing: Printed side face down
A. Side 1
B. Paper feed direction of Side 1
C. Side 2
D. Paper feed direction of Side 2
Single-sided printing: Printed side face up
A. Side 1
B. Paper feed direction of Side 1
Duplex printing: Printed side face up
A. Side 1
B. Paper feed direction of Side 1
C. Side 2
D. Paper feed direction of Side 2