Sony DVS-9000 User Manual page 264

Recalling a key snapshot
For example, the following procedure recalls the state of the M/E-1 key 3
settings.
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Key Snapshots
In the M/E-1 independent key transition control block, press the [K-SS]
button in the key 3 control block, turning it on.
Press the key source name display/key snapshot button corresponding to
the register you want to recall.
The button you pressed lights yellow, and this recalls the key settings
(excluding the key insertion state (on/off) and key priority).