Slightly OT - Calibration of DCS Range?

I have a DCS RD366L Range...
To calibrate the oven, I remove the temperature setting knob to expose two holes each with an adjustment screw.
The inner screw is for the oven's calibration, but...
What is the outer screw for? (It seems related to the calibration, but I can't figure out just what it does.)
Many thanks,

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