Sony DVS-9000 User Manual page 25

Simultaneously changing the background and keys
You can change any of the four keys (downstream keys on the PGM/PST bank)
and the background at the same time.
Selecting the key priority
If a number of keys are already inserted in the current video, you can check or
change the key priority, that is to say, the order in which the keys are overlaid.
When a key priority ([KEY PRIOR]) is selected as the next transition, you can
also change the key priority in the new video.
For details of this operation, see "Key Priority Setting" (page 179).
Key 1
Transition
Changing the background and key 2 simultaneously
Key 1
Transition
Key 2
Changing the background and keys 1 to 4 simultaneously
Key 2
Key 4
Key 3
Transitions
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