Yamaha O2R Owner's Manual page 238

Fader Edit
When you record a fader overdub, this display shows the previously
recorded level and the new fader setting, plus an arrow indicating which
direction the fader will have to be moved to return to the previous level.
Refer to the following diagram:
If the fader is moved to a position lower
than the previously recorded position
Automation 137
If the fader is moved to a position higher
than the previously recorded position
Digital Recording Console 02R User's Guide