Hitachi SK-HD2200 Operating Instructions Manual page 22

Facility names and functions E
E2
E1
E11
E11 Return Signal selection (RET1&RET2)
Selects RET-1/RET-2 input.
Selected return video is displayed on view finder while this button is pressed.
E10
E4
E8
E9
10
E5 D4
E6
E7