Sony DVS-7300 User Manual page 136

Keys
4
5
4-52
Chapter 4 Basic Operations for Image Creation
Press one of F4 through F6 to select the type of signal used for key
source: the same as the key fill signal, or a different signal.
F4 (KEY BUS): Use the signal selected on the key fill bus for the key
source (self-keying). This selection automatically switches the key
source bus to the same signal as the key fill bus, and it is no longer
possible to make a key source bus selection with the cross-point
buttons.
F5 (AUTO SELECT): Use the key source signal allocated to this key
fill signal in a setup menu. The default is to be the same as the key
fill signal (self-keying). This selection also disables key source bus
selection with the cross-point buttons.
F6 (SPLIT): Use the video signal selected on the key source bus.
If you selected F6 (SPLIT) in step 4, select the key source signal using
the cross-point buttons, as follows.
Press the KEY 1 button in the key control section to delegate the key
control section to keyer 1, then hold down the SPLIT button and press
the required cross-point button in the K1 row (BKDS-7012/7021/7022)
or K row (BKDS-7011/7023), or in the auxiliary bus bank.