Note sure about this (I'm not at my console and not having manuals in my hand), but isn't this for switching mode of the JOG WHEEL while controlling your DAW (remote layer)?
That seems to be right. In Mackie Control for Digital Performer mode, I can use the jog wheel to scroll through the sequence without being in the Remote layer... I can just push the Jog/Shuttle button with the mixer in ANY layer and DP responds. Sweet.