Sony CCP-8000 Series User Manual page 248

Returning the key adjustment values to their defaults
Holding down a key type button ([LUM], [LIN], [CRK], [CVK], or [PTN])
recalls the key default values (page 202).
Key modify clear
When an M/E delegation button is held down, holding down a key delegation
button together returns the key settings to the initial status settings.
For details of the initial status, see "Selecting the State After Powering On
(Start Up Menu)" in Chapter 18 (Volume 3).
Key Setting Operations With the Key Control Block
247